Firefox has been very slow and the help topics suggested resetting it. Unfortunately, I forgot to do this out of Sandboxie. Now upon opening Firefox, I get the message that "bookmarks and history system will not be functional because one of Firefox's files is in use by another application. Some security systems can cause this problem." I am also instructed to close everything down and fix the problem, but don't know how to do this. I can access bookmarks and history if I open Firefox unsandboxed, but I don't want to do this.