Restart Firefox
Close Firefox completely: From the menu at the top of the Firefox windowbar, select File and then select the Quit menu item.
Clear cookies and cache
Many problems with loading web pages can be resolved by clearing Firefox's cookies and cache:
1. Click on the Tools menu and select Clear Recent History... to bring up the Clear Recent History window
2. In the Time range to clear drop-down menu, select Everything
3. Click the arrow next to Details to display the list of items to clear, then select the following items:
* Cache
* Cookies
4. Click Clear Now.
For more information, see Clear Recent History. http://support.mozilla.com/en-US/kb/Clear+Recent+History
Troubleshoot extensions and themes
Sometimes add-ons for Firefox (extensions or themes) can cause problems. To confirm whether your problem is caused by an add-on, launch Firefox's Safe Mode:
1. Close down Firefox completely: At the top of the Firefox window, click the File menu, and select the Quit menu item. 2. Go to your Terminal and run:
firefox -safe-mode
3. In the Firefox Safe Mode dialog, click Continue in Safe Mode. 4. Test for your problem.
If the problem does not occur in Safe Mode, an extension or theme is likely the cause. For more information about troubleshooting extensions and themes, and how to narrow down which add-on is causing problems, see http://support.mozilla.com/en-US/kb/Troubleshooting+extensions+and+themes
Reset preferences
If the problem was not fixed by disabling add-ons, you may need to revert changes you've made to Firefox's configuration:
1. Close down Firefox completely: At the top of the Firefox window, click the File menu, and select the Quit menu item. 2. Go to your Terminal and run:
firefox -safe-mode
You may need to specify the Firefox installation path (e.g. /usr/lib/firefox-3.5). Firefox should start up with a Firefox Safe Mode dialog.
3. In the Firefox Safe Mode dialog, click to put a check mark by Reset all user preferences to Firefox defaults and Reset toolbars and controls. 4. To apply your changes, click Make Changes and Restart.
Troubleshoot plugins
Sometimes plugins for Firefox (such as Adobe Reader, Flash, Java, QuickTime, RealPlayer, and Windows Media Player) can cause problems. 3:
1. Exit Firefox cleanly. 2. If you have this directory, rename it:
mv ~/.mozilla/plugins ~/.mozilla/plugins.save
3. Open the Add-ons Window by clicking the Tools menu and selecting Add-ons 4. Click on the Plugins icon at the top of the Add-ons window. 5. Click each plugin in the list and then click Disable. 6. Test for your problem.
For more information about various plugins, and what to do if you find the plugin that causes problems, see the Troubleshooting plugins article. http://support.mozilla.com/en-US/kb/Troubleshooting+plugins
Make a new profile
A corrupt profile can cause various problems with Firefox. You can try to make a new profile test whether that solves the problem, and if so, copy your data (bookmarks, saved passwords, etc.) to the new profile.
Important: Before you can start the Profile Manager, Firefox must be completely closed.
If Firefox is already included in your Linux distribution or if you have installed Firefox with the package manager of your Linux distribution:
1. Exit Firefox. To close Firefox, at the top of the Firefox window, select the File menu, and then select Quit. 2. In Terminal run:
/usr/bin/firefox -ProfileManager
3. To start the Create Profile Wizard, click Create Profile... in the Profile Manager.
4. Click Next and enter the name of the profile. Use a profile name that is descriptive, such as your personal name. This name is not exposed on the Internet.
5. You can also choose where to store the profile, which is useful if you plan on exporting your data and settings to another computer or setup in the future. To choose its storage location on your system, click Choose Folder....
*
Note: If you choose a custom location for the profile, store it in a new or clean folder. When you choose to remove the profile, all contents stored in the same folder are removed.
6. To create the new profile, click Finish.
7. Click on the newly created profile in the Profile Manager and click Start Firefox.
Test to see if your problem occurs with the new profile. If it doesn't, you can copy your data to the new profile - see Recovering important data from an old profile for instructions. For troubleshooting purposes, only copy the files that correspond to your bookmarks and saved passwords.
See also:
http://fedoraproject.org/wiki/How_to_debug_Firefox_problems http://support.mozilla.com/en-us/kb/basic+troubleshooting