I forgot to mention. This only happens to firefox. If I am running other programs and firefox at the same time, only firefox gets stuck.

You can check for problems with the sessionstore.js file in the Firefox profile folder that store session data.

• Help > Troubleshooting Information > Profile Directory: Show Folder (Linux: Open Directory; Mac: Show in Finder)
• http://kb.mozillazine.org/Profile_folder_-_Firefox
• http://kb.mozillazine.org/Multiple_profile_files_created

Deleting sessionstore.js will cause App Tabs and Tab Groups and open and closed (undo) tabs to get lost and you will have to recreate them (make a note or bookmark them if possible).

Start Firefox in Safe Mode to check if one of the extensions (Firefox/Tools > Add-ons > Extensions) or if hardware acceleration is causing the problem.

• Switch to the DEFAULT theme: Firefox/Tools > Add-ons > Appearance
• Do NOT click the Reset button on the Safe Mode start window

• https://support.mozilla.org/kb/Safe+Mode
• https://support.mozilla.org/kb/Troubleshooting+extensions+and+themes

Hi, I can't find "Profile Directory: Show Folder." (Help > Troubleshooting Information > Profile Directory: Show Folder). Is it under "application basics" or something else?

And there is no "Tool" when opened in safe mode. (Switch to the DEFAULT theme: Firefox/Tools > Add-ons > Appearance ).

Separate Issue; Update your Flash Player Version 17.0.0.169
https://www.adobe.com/products/flashplayer/distribution3.html Shockwave Director Version 12.1.7.157 http://get.adobe.com/shockwave/

firefox001 said

Hi, I can't find "Profile Directory: Show Folder."

Type about:support in the address bar and press enter.

Under the page logo on the left side you will see Application Basics. Under this find Profile Folder. To it’s right press the button Show Folder. This will open your file browser to the current Firefox profile. Now Close Firefox.

firefox001 said

Switch to the DEFAULT theme

Type about:addons<enter> in the address bar to open your Add-ons Manager. Hot key; <Control>(Mac:<Command>)<Shift> A)

On the left side of the page, select Appearance.. Then Default.

Thanks. Now I think I have pinpointed the problem. When I disable half of extensions, this problem is solved. And when firefox is running on safe mode, it doesn't have this problem. Now, how do I solve this without disabling any of the extensions?

firefox001 said

how do I solve this without disabling any of the extensions?

The only way to tell what extension is causing the issue is to turn it off.

firefox001 said

When I disable half of extensions, this problem is solved

Good. Now turn the extensions on One By One until the problem comes back. Now you know the problem. Disable that one, and re-enable the others. Then restart Firefox.

If you have many extensions then first enable half of the extensions to test which half has the problem. Continue to divide the bad half that still has the issue until you find which one is causing it.

• https://support.mozilla.org/kb/Troubleshooting+extensions+and+themes

I tried disabling them one by one and figuring out which one. But none of them alone caused the problem. That is, when I disabled only one of the extensions (any of them), that didn't fix the problem. It was when I disabled the first half of all extensions was the problem solved. So I think it is because of that half of the extensions altogether that cause the problem? Is that possible?

Yes. It has happen that two or more add-ons don't like each other. Can you post what you have disabled for us to look over?

Type about:support in the address bar and press Enter. Under the main banner, press the button; Copy Text To Clipboard.. Then in the reply box at the bottom of this page, do a right click in the box and select Paste. This will show us your system details. No Personal Information Is Collected.

Here is the list of the extensions I disabled (then the problem is gone): Adblock plus Classic Theme Restorer Default full zoom Dictionary tooltip Netvidoehunter

System details:

Application Basics

Name: Firefox Version: 36.0.1 User Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:36.0) Gecko/20100101 Firefox/36.0 Multiprocess Windows: 0/2

Crash Reports for the Last 3 Days

All Crash Reports

Extensions

Name: Adblock Plus Version: 2.6.9 Enabled: true ID: {d10d0bf8-f5b5-c8b4-a8b2-2b9879e08c5d}

Name: Classic Theme Restorer Version: 1.3.1beta8 Enabled: true ID: ClassicThemeRestorer@ArisT2Noia4dev

Name: Default Full Zoom Level Version: 4.6.1 Enabled: true ID: {D9A7CBEC-DE1A-444f-A092-844461596C4D}

Name: Dictionary Tooltip Version: 1.7 Enabled: true ID: {C6128004-4838-4708-9A97-BB172D17767D}

Name: NetVideoHunter Version: 1.18 Enabled: true ID: netvideohunter@netvideohunter.com

Name: NoSquint Version: 2.1.9 Enabled: true ID: nosquint@urandom.ca

Name: RightToClick Version: 2.9.5 Enabled: true ID: {cd617375-6743-4ee8-bac4-fbf10f35729e}

Name: Youtube Video Replay Version: 35.1 Enabled: true ID: {e1aaa9f8-4500-47f1-9a0a-b02bd60e4076}

Name: 新同文堂 (New Tong Wen Tang) Version: 0.4.0.9.1 Enabled: true ID: {22870005-adef-4c9d-ae36-d0e1f2f27e5a}

Graphics

Adapter Description: Mobile Intel(R) 4 Series Express Chipset Family Adapter Drivers: igdumd64 igd10umd64 igdumdx32 igd10umd32 Adapter RAM: Unknown Device ID: 0x2a42 DirectWrite Enabled: false (6.1.7600.16972) Driver Date: 2-11-2011 Driver Version: 8.15.10.2302 GPU #2 Active: false GPU Accelerated Windows: 0/2 Basic (OMTC) Subsys ID: 02be1028 Vendor ID: 0x8086 WebGL Renderer: Google Inc. -- ANGLE (Mobile Intel(R) 4 Series Express Chipset Family Direct3D9Ex vs_3_0 ps_3_0) windowLayerManagerRemote: true AzureCanvasBackend: skia AzureContentBackend: cairo AzureFallbackCanvasBackend: cairo AzureSkiaAccelerated: 0

Important Modified Preferences

accessibility.typeaheadfind.flashBar: 0 browser.cache.disk.capacity: 348160 browser.cache.disk.smart_size_cached_value: 358400 browser.cache.disk.smart_size.first_run: false browser.cache.disk.smart_size.use_old_max: false browser.cache.frecency_experiment: 3 browser.link.open_newwindow: 2 browser.places.smartBookmarksVersion: 7 browser.search.update: false browser.sessionstore.resume_from_crash: false browser.sessionstore.upgradeBackup.latestBuildID: 20140417185217 browser.startup.homepage: www.google.com browser.startup.homepage_override.buildID: 20150305021524 browser.startup.homepage_override.mstone: 36.0.1 browser.tabs.warnOnClose: false browser.zoom.full: false browser.zoom.siteSpecific: false dom.event.clipboardevents.enabled: false dom.mozApps.used: true extensions.lastAppVersion: 36.0.1 font.internaluseonly.changed: false font.name.serif.x-western: Arial Rounded MT gfx.direct2d.disabled: true gfx.direct3d.last_used_feature_level_idx: 1 layers.acceleration.disabled: true media.gmp-gmpopenh264.lastUpdate: 1426469717 media.gmp-gmpopenh264.version: 1.3 media.gmp-manager.lastCheck: 1430009979 mousewheel.withcontrolkey.action: 3 network.cookie.prefsMigrated: true places.database.lastMaintenance: 1429901372 places.history.expiration.transient_current_max_pages: 44773 plugin.disable_full_page_plugin_for_types: application/pdf,audio/wav,audio/x-wav plugin.importedState: true plugin.state.np32dsw: 2 plugin.state.npctrl: 2 plugin.state.npgoogletalk: 2 plugin.state.npgoogleupdate: 2 plugin.state.npo1d: 2 plugin.state.nppdf: 2 plugin.state.npqtplugin: 2 print.printer_doPDF_v7.print_bgcolor: false print.printer_doPDF_v7.print_bgimages: false print.printer_doPDF_v7.print_colorspace: print.printer_doPDF_v7.print_command: print.printer_doPDF_v7.print_downloadfonts: false print.printer_doPDF_v7.print_duplex: 1515870810 print.printer_doPDF_v7.print_edge_bottom: 0 print.printer_doPDF_v7.print_edge_left: 0 print.printer_doPDF_v7.print_edge_right: 0 print.printer_doPDF_v7.print_edge_top: 0 print.printer_doPDF_v7.print_evenpages: true print.printer_doPDF_v7.print_footercenter: print.printer_doPDF_v7.print_footerleft: &PT print.printer_doPDF_v7.print_footerright: &D print.printer_doPDF_v7.print_headercenter: print.printer_doPDF_v7.print_headerleft: &T print.printer_doPDF_v7.print_headerright: &U print.printer_doPDF_v7.print_in_color: true print.printer_doPDF_v7.print_margin_bottom: 0.5 print.printer_doPDF_v7.print_margin_left: 0.5 print.printer_doPDF_v7.print_margin_right: 0.5 print.printer_doPDF_v7.print_margin_top: 0.5 print.printer_doPDF_v7.print_oddpages: true print.printer_doPDF_v7.print_orientation: 0 print.printer_doPDF_v7.print_page_delay: 50 print.printer_doPDF_v7.print_paper_data: 1 print.printer_doPDF_v7.print_paper_height: 11.00 print.printer_doPDF_v7.print_paper_name: print.printer_doPDF_v7.print_paper_size_type: 0 print.printer_doPDF_v7.print_paper_size_unit: 0 print.printer_doPDF_v7.print_paper_width: 8.50 print.printer_doPDF_v7.print_plex_name: print.printer_doPDF_v7.print_resolution: 1515870810 print.printer_doPDF_v7.print_resolution_name: print.printer_doPDF_v7.print_reversed: false print.printer_doPDF_v7.print_scaling: 1.00 print.printer_doPDF_v7.print_shrink_to_fit: true print.printer_doPDF_v7.print_to_file: false print.printer_doPDF_v7.print_unwriteable_margin_bottom: 0 print.printer_doPDF_v7.print_unwriteable_margin_left: 0 print.printer_doPDF_v7.print_unwriteable_margin_right: 0 print.printer_doPDF_v7.print_unwriteable_margin_top: 0 privacy.sanitize.migrateFx3Prefs: true storage.vacuum.last.index: 1 storage.vacuum.last.places.sqlite: 1427658228

Important Locked Preferences

JavaScript

Incremental GC: true

Accessibility

Activated: false Prevent Accessibility: 0

Library Versions

NSPR Expected minimum version: 4.10.7 Version in use: 4.10.7

NSS Expected minimum version: 3.17.4 Basic ECC Version in use: 3.17.4 Basic ECC

NSSSMIME Expected minimum version: 3.17.4 Basic ECC Version in use: 3.17.4 Basic ECC

NSSSSL Expected minimum version: 3.17.4 Basic ECC Version in use: 3.17.4 Basic ECC

NSSUTIL Expected minimum version: 3.17.4 Version in use: 3.17.4

Experimental Features

I use Adblock plus and Classic Theme Restorer. Restore these and restart.

If there is no issue, restore one of the below. If no problem after restarting, add another and restart. Let us know how you are doing.

Default full zoom Dictionary tooltip Netvidoehunter

I just noticed; Security Issue: Update your Flash Player Version 17.0.0.169
https://www.adobe.com/products/flashplayer/distribution3.html

See if there are updates for your graphics drivers https://support.mozilla.org/kb/upgrade-graphics-drivers-use-hardware-acceleration

You need to disable all extensions as a start and then enable them one by one and leave the ones that are already enabled in enabled state. Close and restart Firefox if the extension needs a restart and check if it still works.

Taking all your suggestions, I updated Adobe flash player. Checked but there is nothing to update on graphic card. Checked the extensions you mentioned (and disable and enable as suggested), ok, once I disabled this extension "dictionary tooltip 1.7," firefox worked just fine. No lagging on closing firefox windows anymore.

(But updating adobe flash player seems to be a bad idea. Now Firefox, in general, is running a little slower more often. But I figure I can always downgrade flash player and it doesn't seem to cause problem with running firefox on my computer.) Anyway, do I have to disable this "dictionary tooltip" to fix this problem?

Awww, too bad. I looked hard for a good English dictionary add-on. I am a foreigner and really need a somple English dictionary surfing any website. Most English dictionary add-on is too fancy. Click on the word and it will show up like, which one do you want, dictionary, thesaurus, or something else, or which dictionary do you want your definition from etc.

I just want a simple English dictionary add-on that will give me definition right away. With that fancy dictionary add-on, my clicking on one page doubles or triples. It's really bad when I have to click twenty times, now becoming forty times (or sixty times) just for one page. So does anyone have suggestions about what simple English dictionary add-on there are?

That was very good work. Well Done. Please flag your last post as Solved Problem so others will know.

Disable or remove that add-on. Then contact their support site.

Go to the Mozilla Add-ons Web Page {web link} (There’s a lot of good stuff here) and search for what you want.