I ran into a problem on my Windows 7 Ultimate x64 on my MSI CR700x notebook a few weeks ago. For some reason, when logging in, after entering my password, I was stuck at the Welcome screen, that blue "waiting cursor" was still circulating, but nothing happened even after 10 minutes. Sometimes I didn't even get to the login screen, because after the "Starting Windows" screen, I was stuck at a black screen, where only the mouse cursor was shown. In both cases, the only way to quit was to shut down the computer using the power button. (in safe mode I could log in without problems)
To workaround, I booted up from the recovery CD, and chose System Restore. I could only choose restore points related to Updates, after this, I could boot up and log in one time (!), however, after a second restart the same problem occured, and to even use the PC I needed to do a system restore from the recovery CD before each start. Automatic updates were turned on. After a few days I've had enough of it, so I decided to reinstall Windows, but after 3-4 days the same problem occured again. (updates were still turned on). So for a few weeks I even went back to XP. Now I have Windows 7 installed again, but with Automatic Updates turned off, and the system is working properly for a week now.
But I don't want to keep Automatic Updates turned off. Which update causes these problems, and how to uninstall/disable it? Or is there a fix for that since then if it's a known/popular problem?