How many updates are there? Vista is notorious for this. If it's a reasonably low number like 10, try methodically just doing 1 at a time (slow and painful I know) until the problem re-occurs knowing which is which and that you can always do another restore. After this, complete all updates without the one causing issue and create a new restore point so you don't have to do the other ones again and leave the bad update alone and contact microsoft about this. Glad you are back up and running but it's useful to know what exactly is causing the problem. Please keep me posted!