Sometimes a problem with Firefox may be a result of malware installed on your computer, that you may not be aware of.

You can try these free programs to scan for malware, which work with your existing antivirus software:

• Microsoft Safety Scanner
• MalwareBytes' Anti-Malware
• TDSSKiller - AntiRootkit Utility
• Hitman Pro
• ESET Online Scanner

Microsoft Security Essentials is a good permanent antivirus for Windows 7/Vista/XP if you don't already have one.

Further information can be found in the Troubleshoot Firefox issues caused by malware article.

Did this fix your problems? Please report back to us!

Note a quick and easy way of getting a Firefox install is to use the unofficial build of Firefox Portable. That can be used as an additional browser and may be a good temporary work around and a standby spare browser

• http://portableapps.com/apps/internet/firefox_portable

Firefox portable may be installed without affecting your ordinary working copy of Firefox or your Firefox settings.

Obviously Firefox should not need reinstalling every time you use it. I tend not to use Windows and it is a while since I had Windows XP. IIRC firefox.exe would be a file not a folder.

Try a clean reinstall of Firefox, noting that involves deleting program files NOT profile files. Also make sure you use an official download when obtaining the installer.

Post back with how you get on

Certain Firefox problems can be solved by performing a Clean reinstall. This means you remove Firefox program files and then reinstall Firefox. Please follow these steps:

Note: You might want to print these steps or view them in another browser.

1. Download the latest Desktop version of Firefox from http://www.mozilla.org and save the setup file to your computer.
2. After the download finishes, close all Firefox windows (click Exit from the Firefox or File menu).
3. Delete the Firefox installation folder, which is located in one of these locations, by default: (Windows:)
   • C:\Program Files\Mozilla Firefox
   • C:\Program Files (x86)\Mozilla Firefox
4. Now, go ahead and reinstall Firefox:
   1. Double-click the downloaded installation file and go through the steps of the installation wizard.
   2. Once the wizard is finished, choose to directly open Firefox after clicking the Finish button.

More information about reinstalling Firefox can be found here

• Troubleshoot and diagnose Firefox problems _5-reinstall-firefox

WARNING: Do not run Firefox's uninstaller or use a third party remover as part of this process, because that could permanently delete your Firefox data, including but not limited to, extensions, cache, cookies, bookmarks, personal settings and saved passwords. These cannot easily be recovered unless they have been backed up.

Please report back to see if this helped you!

Thank you.

Go to Mozilla.org and download the Full installed. After, remove the current Firefox. When you are done, run the Full installer.