I just rebuilt my machine, with three HDDs on SATA interfaces, and have an odd behaviour. The HDD LED flashes constantly, at a rate of about twice a second, even when the machine is apparently doing nothing. Task Manager doesn't provide me with any clues as to what's going on - other than System Idle Process occupying ~95% of CPU time (out of total typical 2-3%). I've got antivirus and spyware software installed and do regular scans to keep everything clean, and I've tried stopping various stuff that run in the backgound, but nothing stops the HDD light flashing all the time. Any ideas as to how I can find what's accessing the HDDs all the time?