One of your installed extensions might be causing that problem.

Do you have that problem when running in the Firefox SafeMode?
A troubleshooting mode.
You can open the Firefox 4.0 SafeMode by holding the Shft key when you use the Firefox desktop or Start menu shortcut. Or use the Help menu item, click on Restart with Add-ons Disabled... while Firefox is running.
To exit the Firefox Safe Mode, just close Firefox and wait a few seconds before using the Firefox shortcut to open it again.

If not, see this:
http://support.mozilla.com/en-US/kb/troubleshooting+extensions+and+themes

It was not the extensions but your link led to resetting my preferences. That seems to have worked. However, I did lose about 100 tabs I had open. I'm a little sick about that. Wish I had been warned that might happen.

My problem is not solved. Now, a day after I thought it was fixed (and losing 100 tabs in the process), the arrow keys are not working again. The only changes I have made were to 1) not allow 3rd party cookies and 2) change to the option to show my windows and tabs from the previous session when I restart Firefox. Yesterday's fix was working up until about 10 minutes ago when I sat down to send an email.

I am starting to think one of the websites I am loading is affecting the ability to edit text. When I start with one tab, it works fine. I am now loading one at a time and testing the editing with each one. I have 16 open now on my way to 70 or so. This will take awhile because I actually have to get some work done.

How large is the file sessionstore.js in the Firefox Profile Folder ?

• Help > Troubleshooting Information > Profile Directory: Open Containing Folder

• http://kb.mozillazine.org/Session_Restore

The one currently is 110 KB. Looks like there is one saved from Feb 14 at 8.564 MB. I have 59 tabs open. Several of them from earlier were duplicates because I could not find them where I was looking (looking at the end of the row of tabs instead of adjacent to the tab that spawned the new tab). So I have 59 tabs open and things seem to be working fine after several hours.

Saving 8 MB every 10 seconds will cause a lot of extra strain, so if it happens again then check the size of that file. If you open a lot of links in one tab then Firefox will also save that tab history.

Update. It happened again. I checked my sessionstore file and it was up to 545 kb. I shift-opened Firefox and it reset everything in that folder. Sessionstore went to 0kb. So I did not open Firefox in the safe mode. I simply reopened it and it has reset the sessionstore. It is working fine again. Will keep an eye on this. Still would like to know why this is happening. Why is sessionstore causing the problem and why is sessionstore getting out of hand?

Update. It has been awhile but this problem has recurred. This time is different because I cannot seem to get the sessionstore file to zero out. When I launch in the safe mode, the sessionstore file does not reset. For what it's worth, the problem is the same while running in the safe mode. The session store file is 1,371 kb.

I would still would like to know why this is happening. Why is sessionstore causing the problem and why is sessionstore getting out of hand? Or is sessionstore even the problem, since it has been far larger in size than it was previously and continued to work?

It is possible that there is a problem with the files sessionstore.js and sessionstore.bak in the Firefox Profile Folder.

Delete the files sessionstore.js and sessionstore.bak in the Firefox Profile Folder.

• Help > Troubleshooting Information > Profile Directory: Open Containing Folder
• http://kb.mozillazine.org/Profile_folder_-_Firefox
• http://kb.mozillazine.org/sessionstore.js

If you see files sessionstore-##.js with a number in the left part of the name like sessionstore-1.js then delete those as well.

Deleting sessionstore.js will cause App Tabs and Tab Groups to get lost, so you will have to create them again (make a note).

See:

• http://kb.mozillazine.org/Session_Restore

I had the problem again today. I deleted all the sessionstore files including the .bak. Restarted and reloaded the tabs. The problem continued immediately. Size of sessionstore at the time was 10 KB. I closed Firefox and restarted it. The problem continues. Current size of sessionstore.js is 98 KB.

Are you sure sessionstore is the problem?

Does it still happen with only one tab open?

Do you have security (anti-virus) software that might interfere with Firefox saving a new sessionstore.js file?

You can try to exclude the Firefox Profile Folder from the real-time scanning to see if that helps.

• http://kb.mozillazine.org/Profile_folder_-_Firefox

Problem is back and much worse with Firefox 6. Now my sessionstore.js file is deleted whenever I close Firefox. When I reopen Firefox there is one blank tab. When I open a site where I can edit text, the editor works normally. But when I open my normal 33 tabs, I cannot edit normally.

Oh and all my history is deleted when I shut Firefox down. Bookmarks are fine. When I restart all my previously saved tabs, there is no history associated with the tabs.

Make sure that you do not run Firefox in permanent Private Browsing mode.

• https://support.mozilla.com/kb/Private+Browsing
• You enter Private Browsing mode if you select: Tools > Options > Privacy > History: Firefox will: "Never Remember History"
• To see all History and Cookie settings, choose: Tools > Options > Privacy, choose the setting Firefox will: Use custom settings for history
• Deselect: [ ] "Permanent Private Browsing mode"

Als0, Tools -> Options -> Privacy settings -> Remove Checkmark from Clear History when Firefox closes

Check and tell if its working.

Tools -> Options -> Privacy settings -> Remove Checkmark from Clear History when Firefox closes

Thank you mha007. That fixed the history saving part, which technically was off topic for the editing issue. Now I still have the issue with editing as described in the opening message in this thread. What was not working in FF4.0 is not working in FF6.0.

Uninstall AVG Safe Search from your AVG Antivirus. Disable/Remove it from Firefox too. This extension has been reported as causing various problems in Firefox.

Troubleshooting extensions and themes

• https://support.mozilla.com/en-US/kb/Troubleshooting%20extensions%20and%20themes

Remove Multiple Java Console extensions

• http://kb.mozillazine.org/Java#Multiple_Java_Console_extensions

Clear Cookies & Cache

• https://support.mozilla.com/en-US/kb/Template:clearCookiesCache

Clear the Network Cache

• https://support.mozilla.com/en-US/kb/How%20to%20clear%20the%20cache#w_clear-the-cache

Troubleshooting plugins

• https://support.mozilla.com/en-US/kb/Troubleshooting%20plugins

-> click Firefox button and click Options (if you don't have Firefox button, Tap ALT key or press F10 to show the Menu bar -> go to Tools Menu)

• Advanced panel -> General tab -> Remove Checkmarks from:
  • 1) Always use cursor keys to navigate within pages
  • 2) Search for text when i start typing
  • 3) Warn me when websites try to redirect or reload the page
  • 4) Use Auto-Scrolling
  • 5) Use Hardware Acceleration when available

Check and tell if its working.

Still no joy.

I cannot uninstall AVG Safe Search from my AVG Antivirus because I cannot find it.

I cannot disable or remove it from Firefox because it is already disabled by version 6.0.

I cannot disable or remove Java Console extensions for the same reason.

I don't have a Firefox button but there is a setting in Options for clearing history including cache. That setting was checked until you told me to uncheck it in your previous (helpful) reply.

I cleared the network cache.

I disabled all my plugins and restarted.

Editing went fine for about 5 minutes and now it is back to being flukey.