Windows 7 64 bit patch stopped Windows from starting

Last night I had the fun of having to reinstall Windows 7 64 bit edition:

Some or other patch came with the security updates that prevented startup. There was only the initial grey/white progress bar at the bottom and then the PC went into a reboot. This happened several times. The progress bar was usually part of the Windows Startup Repair process which had obviously failed at this point in time.

Safe mode resulted in the same kind of issue including a blue screen. I ended up getting my original DVD out to use the repair tool. The repair tool could not fix Windows either. Using the last known good startup did not work and system recovery failed as well. The repair tool took a while, but at the bottom of the report it finally said that the startup was prevented by a patch. In the end I had to format and start from scratch. That installation also botched up with a restart and a partial repeat of the installation which included having to create users twice as well as having to put in my product key twice. On the second time having to add users, I had to create a different user. In the end, Windows was starting again.