Running Windows XP, I keep noticing that my hard drive is accessing something and when I use the Windows Task Manager to look, I see where the CPU Usage History looks like an EKG with a constant series of regularly spaced, same height spikes in SPU usage that correlate with an increase in the activity on the "processes" tab in the explorer.exe process. I have turned every thing off I can find, scanned the system for spyware with updated McAfee, Ad-Aware, and SpyBot and nothing. Every four or five seconds, though, my CPU usage jumps to 40-50 % and then falls immediately back down. The pattern is repetitive constantly and does seem to involve the hard drive writing or seeking some information. HELP!