92k's worth of cr@p - what can I say? It looks like there's been a backup of some sort done that isn't being deleted. That's an AWFUL lot of stuff to just reappear spontaneously after reboot.
Is the hard disk a single partition - i.e. just the C: drive? Or, has it been split into a couple of drive letters? Just fishing here.
If it's just a single drive, I agree, bugga! If it's partitioned into a couple of drives, that might be where the problem lies. The scanning s/w might not be set to look into all the drives.
Your mate's got a good healthy attitude. A new drive seems like a way out. Please don't be tempted to leave the old drive in the PC when you install a new drive though!
ST