Anybody else seen this behavior? Why would changing a SATA controller to a different mode (AHCI to RAID) cause Windows to become deactivated? No Hard Drive changes were made. I will give it some time to see if it comes back, but this is strange. I do have Media Center installed, possibly the key changes involved with that could be influencing the process. Edit: I got it figured out. It was not changing the controller that caused the deactivation, but the attempted repairs after the system tried to do one. When I changed the controller so the system did not attempt a repair, the system stayed activated.