I've ended up with some files related to a Visual Studio 9.0 Beta Program on my storage drive where I mostly store games. I don't know where they've come from or why they've ended up on that particular drive.
Right, I got it. They're temp files erroneously put in the root of the drive, but why would it then at this page say that it's been fixed with a service pack? https://support.microsoft.com/en-us/kb/950683