Can you try to start Firefox in Safe Mode to see if Firefox works properly with no error? You can start Firefox in Safe Mode below:

• Windows/Mac: Go to Help > Restart with add-ons disabled
• Linux: Run firefox -safe-mode in the Terminal/Konsole

If Firefox opens up fine with no problems, it's probably one of your extensions that's causing the issue. You can re-enable your add-ons one by one until you find the one that causes the issue upon being re-enabled.

Open a new window or tab. In the address bar, type about:config. If a warning screen comes up, press the Be Careful button. This is where Firefox finds information it needs to run. At the top of the screen is a search bar. Enter Scroll or Mouse, and whatever else you can think of. Look at the settings If you think there is a problem, post it here.

I found that after Firefox v29, a LOT of my settings and
add-ons were changed / reset. Try this; Start Firefox in Safe Mode
While you are in safe mode;
Firefox Options > Advanced > General.
Look for and turn off Use Hardware Acceleration.
Then check ALL of your settings. Browser and add-ons. Then restart.

Did not work

Can you start by giving us the troubleshooting information from the Firefox installation that's having problems. This is an essential step in troubleshooting.

• Click the Firefox button at the top left, then click the Help menu and select Troubleshooting Information from the sub-menu. If you don't have a Firefox button, click the Help menu at the top and select Troubleshooting Information from the menu.

Now, a new tab containing your troubleshooting information should open.

• At the top of the page, you should see a button that says "Copy text to clipboard". Click it.
• Now, go back to your forum post and click inside the reply box. Press Ctrl+V to paste all the information you copied into the forum post.

Application Basics

Name: Firefox Version: 29.0 User Agent: Mozilla/5.0 (Windows NT 6.3; WOW64; rv:29.0) Gecko/20100101 Firefox/29.0

Crash Reports for the Last 3 Days

All Crash Reports

Extensions

Name: avast! Online Security Version: 9.0.2018.95 Enabled: true ID: wrc@avast.com

Name: LastPass Version: 3.1.1 Enabled: true ID: support@lastpass.com

Name: Xmarks Version: 4.2.1 Enabled: true ID: foxmarks@kei.com

Important Modified Preferences

browser.cache.disk.capacity: 358400 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.places.smartBookmarksVersion: 6 browser.sessionstore.upgradeBackup.latestBuildID: 20140421221237 browser.startup.homepage_override.buildID: 20140421221237 browser.startup.homepage_override.mstone: 29.0 browser.tabs.warnOnClose: false dom.mozApps.used: true extensions.lastAppVersion: 29.0 gfx.direct2d.disabled: true gfx.direct3d.last_used_feature_level_idx: 0 layers.acceleration.disabled: true network.cookie.prefsMigrated: true places.database.lastMaintenance: 1399426196 places.history.expiration.transient_current_max_pages: 104858 plugin.disable_full_page_plugin_for_types: application/pdf plugin.importedState: true print.printer_CutePDF_Writer.print_bgcolor: false print.printer_CutePDF_Writer.print_bgimages: false print.printer_CutePDF_Writer.print_colorspace: print.printer_CutePDF_Writer.print_command: print.printer_CutePDF_Writer.print_downloadfonts: false print.printer_CutePDF_Writer.print_duplex: 0 print.printer_CutePDF_Writer.print_edge_bottom: 0 print.printer_CutePDF_Writer.print_edge_left: 0 print.printer_CutePDF_Writer.print_edge_right: 0 print.printer_CutePDF_Writer.print_edge_top: 0 print.printer_CutePDF_Writer.print_evenpages: true print.printer_CutePDF_Writer.print_footercenter: print.printer_CutePDF_Writer.print_footerleft: &PT print.printer_CutePDF_Writer.print_footerright: &D print.printer_CutePDF_Writer.print_headercenter: print.printer_CutePDF_Writer.print_headerleft: &T print.printer_CutePDF_Writer.print_headerright: &U print.printer_CutePDF_Writer.print_in_color: true print.printer_CutePDF_Writer.print_margin_bottom: 0.5 print.printer_CutePDF_Writer.print_margin_left: 0.5 print.printer_CutePDF_Writer.print_margin_right: 0.5 print.printer_CutePDF_Writer.print_margin_top: 0.5 print.printer_CutePDF_Writer.print_oddpages: true print.printer_CutePDF_Writer.print_orientation: 0 print.printer_CutePDF_Writer.print_page_delay: 50 print.printer_CutePDF_Writer.print_paper_data: 1 print.printer_CutePDF_Writer.print_paper_height: 11.00 print.printer_CutePDF_Writer.print_paper_name: print.printer_CutePDF_Writer.print_paper_size_type: 0 print.printer_CutePDF_Writer.print_paper_size_unit: 0 print.printer_CutePDF_Writer.print_paper_width: 8.50 print.printer_CutePDF_Writer.print_plex_name: print.printer_CutePDF_Writer.print_resolution: 0 print.printer_CutePDF_Writer.print_resolution_name: print.printer_CutePDF_Writer.print_reversed: false print.printer_CutePDF_Writer.print_scaling: 1.00 print.printer_CutePDF_Writer.print_shrink_to_fit: true print.printer_CutePDF_Writer.print_to_file: false print.printer_CutePDF_Writer.print_unwriteable_margin_bottom: 0 print.printer_CutePDF_Writer.print_unwriteable_margin_left: 0 print.printer_CutePDF_Writer.print_unwriteable_margin_right: 0 print.printer_CutePDF_Writer.print_unwriteable_margin_top: 0 privacy.cpd.offlineApps: true privacy.cpd.siteSettings: true privacy.sanitize.migrateFx3Prefs: true privacy.sanitize.timeSpan: 0 storage.vacuum.last.index: 0 storage.vacuum.last.places.sqlite: 1399426196

Graphics

Adapter Description: Intel(R) HD Graphics 3000 Adapter Description (GPU #2): NVIDIA GeForce GT 555M Adapter Drivers: igdumd64 igd10umd64 igd10umd64 igdumd32 igd10umd32 igd10umd32 Adapter Drivers (GPU #2): nvd3dumx,nvwgf2umx,nvwgf2umx nvd3dum,nvwgf2um,nvwgf2um Adapter RAM: Unknown Adapter RAM (GPU #2): 3072 Device ID: 0x0116 Device ID (GPU #2): 0x0dcd DirectWrite Enabled: false (6.3.9600.16384) Driver Date: 1-29-2014 Driver Date (GPU #2): 3-4-2014 Driver Version: 9.17.10.3347 Driver Version (GPU #2): 9.18.13.3523 GPU #2 Active: false GPU Accelerated Windows: 0/1 Basic Vendor ID: 0x8086 Vendor ID (GPU #2): 0x10de WebGL Renderer: Google Inc. -- ANGLE (Intel(R) HD Graphics 3000 Direct3D9Ex vs_3_0 ps_3_0) windowLayerManagerRemote: false AzureCanvasBackend: skia AzureContentBackend: cairo AzureFallbackCanvasBackend: cairo AzureSkiaAccelerated: 0

JavaScript

Incremental GC: true

Accessibility

Activated: false Prevent Accessibility: 0

Library Versions

NSPR Expected minimum version: 4.10.3 Version in use: 4.10.3

NSS Expected minimum version: 3.16 Basic ECC Version in use: 3.16 Basic ECC

NSSSMIME Expected minimum version: 3.16 Basic ECC Version in use: 3.16 Basic ECC

NSSSSL Expected minimum version: 3.16 Basic ECC Version in use: 3.16 Basic ECC

NSSUTIL Expected minimum version: 3.16 Version in use: 3.16