Why does Windows 7 reboot itself every 2 minutes?

I ran into this issue: I had installed the 320.49-desktop-win8-win7-winvista-64bit-english-whql.exe NVidia GeForce driver.  This forced me to install some type of .NET 4 (extra?) runtime environment.  The next time I booted my computer, Windows 7 would automatically reboot itself after about 2-3 minutes.  If I were in safe mode, it didn't reboot.  This is how I solved it:

1. Booted Windows 7 in safe mode (press F8 when booting)
2. Installed an old NVidia driver, such as 314.07-desktop-win8-win7-winvista-64bit-english-whql.exe
3. Reboot Windows in normal mode
4. Now you have to be real quick before your machine reboots: uninstall the .NET 4 runtime environment that had just been installed.  The uninstaller will ask you to reboot your machine.  Reboot it into normal mode.
5. If all goes well, your system will be back to normal!

You can also try reading the logs in the Event Viewer for some hints.

Similar symptom, different solution: http://social.technet.microsoft.com/Forums/windows/en-US/d7379f4d-9337-4800-9c8b-582fd0c439a7/windows-7-pro-keep-restarting-on-itself-will-not-last-longer-than-2-minutes-but-safemode-works

Ditto: http://www.tomshardware.com/answers/id-1672386/computer-rebooting-pretty-stumped.html