if you have re-installed your Windows Operating System recently and you run your Firefox using the portable edition, then you probably have encountered the following error message when you launch your Firefox browser "The bookmarks and history system will not be functional because one of Firefox's files is in use by another application. Some security software can cause this problem.".  This most likely happened because of file permissions on your Firefox profile.  Your newly created account is probably not listed under the security tab of your portable Firefox installation directory.

Do not panic and start assuming that you lost all your bookmarks and extensions.  The fix for this problem is rather trivial.  Hopefully you make backups every now and then just in case of anything that might go wrong.  I certainly do.

To fix this problem, you need to change the file permissions on your Firefox installation directory.  This error will likely occur for people who use another partition to store their portable applications (like I do).

This will assume that you have admin rights.  If you don't, then grab the person who created your account.

Right-click on your Firefox portable directory and go to the Security tab.  Click on the Advanced button at the bottom of the screen.  You should come up with something similar to the following screen shown below.  Grant full access to your user account or the group you are under.  Make sure to select the two check boxes at the bottom as shown below.



Click OK.  Try to run you Firefox now and hopefully it works.