What are install* eula* and hash code directories sitting on the root of my drive?
Solution 1:
Those are from the Visual C++ 2008 Redistributable package. That's a little mistake on Microsoft's part, they were supposed to be written to the temp directory on the C drive, but instead they end up being written to the root of whichever drive has more free space. They can be deleted.
Microsoft has a knowledge base article at http://support.microsoft.com/kb/950683