It doesn't sound like harddrive failure to me. Most drives, even under ideal circumstances, are fragmented to the point where installations of games or whatever are scattered across the disk. The installer will intentionally write to different parts of the drive depending on the directory structure. If it were a HD failure, something would remain. Icons on the desktop or start menu, the folder in the programs directory or something. If the icon was there and you tried to start it, the computer would react unfavorably. It sounds like it is literally being uninstalled. I have not heard of a virus that will uninstall software. The authors of malware want infect the software you are running so that their code will send back to them bits of information that can then be transformed to monetary gain or the like. So the question remains; who has had access to your computer to play this prank on you? You might want to change your password or add one if nonexistent. Also check the user config to be sure there are not any hidden users lurking about. Disable the guest account if it is active. Secure your wireless network if you have one. Be sure firewall is on and check settings, etc.
This is where I would start.
You could look into the window log files. These might shed some light on the subject.
click the start orb, and type computer management. Expand event viewer and click on windows logs.
A freeware app that might help is
Watch 4 Folder 2.3 available from Softpedia. I don't know your habits, but mine are to leave the computers running 24/7. In this case the utility can be running and minimized to the sys tray to monitor any changes. The changes can also be written to a log file to know what of several monitoring options have occurred.