Not sure if this is a security problem or not. We did a bunch of security scans and none of them came up with anything suspicious. We're just wondering what might be going on with this. After leaving the computer on for some time (a few hours), the memory on my friend's computer (he uses Windows Vista) keeps changing on its own. Each time he refreshes the screen, the hard drive (just the hard drive) keeps coming up with different values for memory (differences include drops of about 3.0GB on its own...memory also has a larger tendency to drop than increase). What is going on and how do we fix it (we're sort of dead stuck on this problem)?