I had sort of the same problem No hardware changes, but did a couple of system restores. Booted up the machine a couple of times and then the next day the infamous you have 3 days to activate. I called in to reactivate and no solid answer why this occurred.
Home based unit-cable internet-not shared-IntelD845-P4 2.6, Geforce4 5600 video, XP prosp1-all patches-updates, d/l and installed zone alarm update,rebooted and got message about hardware changing significantly-"You have 3 days to reactivate"-boot was not completed so no internet connection was available, clicked-"later" and finished boot, ZA setup, then clicked Activation from within Programs menu-still wouldn't connect-other websites OK, so tried by phone -but no installation ID in the activation box-robot voice on the other end was no help-so restored to yesterday, reinstalled ZA update, rebooted, clicked later when the activate box came up- then connected to internet on home page, then clicked open activate wizard and it activated online no prob- doublechecked 'Msoobe'thingie and rebooted just to be sure no recurring activate me every time ( like I've seen in other threads)- question is- it's been 5 months or so since I changed hardware any ( video card),nothing since except last week turning off restore on a couple of partitions...was I triggered by ZA update-or what???TFAI