Oh I get it. This is clearly a case of a registry and some folders for temporary files that have to be cleaned. I recommend to use CCleaner first (clickylinky). First, use the "registry" option of that program to clear windows' registry. Then click the clean button for the temporary files. Last but not least, defragment your system regularly, at least once in two months. I recommend you to use Auslogics Disk Defrag (clickylinky). Maybe it's not the best, but it's free and a very good defragmentation program.
Recommended: configure Firefox in such a manner that, when you exit that browser, it will automatically clean up its temporary files (or ask you whether it should do that). Yet, use CCleaner regularly to make sure nothing stays behind: not from Firefox, neither from Windows.

By the way, this should actually be posted in the "Gamer's Hellp" forum, this place is meant for discussing all kinds of software.

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