More detail might be helpful, but it honestly sounds to me like it might be time to boot into the recovery console, restore from backup, or rebuild the machine, as appropriate.
Before doing so, you'll probably want to troubleshoot the error as much as possible - unplug/disconnect peripheral devices and anything else you possibly can, in case an update is causing driver issues or it's a hardware fault, see if you can get even limited access remotely (TS, psexec, WMI, RemoteRegistry, Remote Event Viewer, etc.), and even consider putting the system drive(s) in another box to narrow it down. (Use identical hardware, or as close to it as you can get, and be cautious. You probably don't want to try this if you don't have a backup, in the event Windows boots up and "helpfully" updates the HAL or the number of processors, because that can permanently destabilize your install.)
Had the same type of issue with some of my older machines and the May (or April?) Windows Updates hosing them to where they wouldn't boot, or would only boot in safe mode sometimes. Wasted a lot of time trying to get them running again, but I ended up resorting to rebuilding 'em, and good riddance for the amount of Windows rot on those ancient things.