Ran into this one while trying to sysprep some machines I was playing around/testing a software deployment with. After a sysprep with OOBE and Generalize, the machine reboots to "autochk not found / skipping autocheck" and then loops with reboots. Nothing I was able to do short of a repair of the OS could help-- Last Known good Configuration didn't help, neither did Safe Mode.

However, I found this posted in some forum with no references at all to whether or not it fixed the issue-- but I tried it, and first shot, no more looping reboots when I sysprep my "golden" VM.

diskpart

list volumes

select volume 1

attributes volume

attributes volume clear nodefaultdriveletter