I had 200+ files which had public key token: "90ba9c70f846762e" (have to do a sort by of course), these are all ati files. I've found it via google because vision control refused to start. The fix was to delete all the files in there, and do a reinstall. I might be an isolated case of these files since I went through a lot of driver installs/cleanups and so on in a few days. But none of the cleaners removed them, I had to delete them by hand in safe mode. This folder is some kind of a Global assembly cache... Some further googling is to be made about the purpose of this. I'm guessing you will know for what is ti for.