Extension prevented Firefox from closing properly

Norton IPS, Norton Toolbar, and Skype 4.0 are all known to prevent Firefox from closing properly. Firefox is still running, but no windows are open.

1. Right-click on an empty spot in the Windows task bar and select Task Manager (or press Ctrl+Shift+Esc).
   
   
   
   
2. When the Windows Task Manager opens, select the Processes tab.
   
   
   
   
3. Select the entry for firefox.exe (press F on the keyboard to find it) and click End Process.
4. Click Yes in the "Task Manager Warning" dialog that appears.
   
   
   
   
5. Repeat the above steps to end any additional firefox.exe processes, if more than one entry is found, then exit the Windows Task Manager.
6. Start Firefox normally.
7. At the top of the Firefox window, click on the Tools menu, and select Add-ons.
8. Select the Extensions panel.
9. (If it is listed) Select Norton IPS and click Disable.
10. (If it is listed) Select Norton Toolbar and click Disable.
11. (If it is listed) Select Skype 4.0 and click Disable.
12. Click on Restart Firefox.

There was an error launching the application

This error indicates that either Firefox is not installed or your shortcut to it is incorrect. Make sure that Firefox is installed at the location specified by the shortcut. If it isn't, install Firefox if necessary, then modify the shortcut to point to the correct location.

The program must close to allow a previous installation attempt to complete. Please restart.

If you get a message saying The program must close to allow a previous installation attempt to complete. Please restart. when you start Firefox, see The program must close to allow a previous installation attempt to complete.

Error opening file for writing...

If you receive the above error when launching Firefox on a Windows system, you may be required by Firefox to log in as an administrator. You can either reboot the computer or, if you have an administrator account, you can execute the program as an administrator.

1. Find the firefox.exe program file in the Firefox application folder on your system.
2. Right-click the icon.
   • (Windows XP) Select Run As.... Select The following user:. From the User name drop-down, select Administrator or another user that has administrator privileges. Enter the password required to log in to this account. Click OK.
   • (Windows 7 and Vista) Select Run As Administrator.... Complete a similar set of steps, as those listed above.
3. The Firefox application is started using the administrator Windows account. The user that was used to log in to Windows at startup is still the active one.

Firefox 3 will not start on OSX 10.3.9 or earlier

Firefox 3 will not start on Windows 98/ME or earlier

Mozilla has stopped supporting OSX 10.3.9Windows 98/ME and earlier in Firefox 3.0 and higher. None of these operating systems are supported by AppleMicrosoft (and have not been for quite some time) and have multiple vulnerabilities that will remain unpatched. As such, you have the following options:

1. You can switch to another operating system. This is the most secure option. If you don't want to pay for a new operating system, you can get any of a number of versions of Linux which can run Firefox 3+ and can run on older machines. This ensures you have a completely secure system and access to all the great new features in Firefox 3+.
2. You can continue to use Firefox 2 which you can get from: our FTP siteour FTP site. Just because the browser will no longer receive security updates doesn't mean it will simply stop working. You will be using unsupported software on an unsupported operating system which poses a significant security risk.

Firefox will not start on Linux

If you installed Firefox outside of your package manager, make sure that your system has the libraries listed in the system requirements.