Is there an actual known cause of this? I maintain 6 PCs at a local school, all of them have identical hardware and software. I attempted to upgrade all of them from RS2 to RS3 today with an RS3 image containing the latest CU and SSU. 4 of the 6 went off without a hitch and 2 of them stopped at 33% after the 2nd reboot. I don't actually need to fix these (will just pave over them) but I would love to know what actually causes this. Reports seem to indicate that at 33% drivers are being installed and some people have reported that removing a wireless card fixed the lockup but in my case all 6 systems are identical so hardware seems unlikely.