http://support.microsoft.com/default...en-us%3B174630
or..
use a PE with regedit32 and then follow instructions on ms website for locating the key that needs to be changed from 1 to 0.
(If you chose to do the PE(bartpe recommended), this will only show you the actual message on a blue screen (bsod). go from there and post the message you get or google it or search on msdn/forums)
good luck