I re-booted in safe-mode, and ran anti-malware scans (all just updated) - Microsoft Security Essentials, AntiMalwareBytes and SuperAntiSpyware. Nothing showed up, but the HD activity stopped. I also downloaded and ran Autoruns, but I couldn't see anything that was obviously alien.
Is there a reasonable explanation for this (perhaps index rebuilding, or something)? If not, is there a way I can tell next time what's causing this burst of activity, so I can deal with it?
Edited by Orange Blossom, 25 March 2011 - 08:28 AM.
Moved to AII from Vista. ~ OB