"One of my PCs won't shut down or restart." and then state "I can't even get a menu by pressing ctr+alt+del, the only way I can get a task manager is by executing taskmgr.

Using msconfig, I removed programs at a start up from booting up at the start up as well as all non-Microsoft programs at the boot up. I also checked the processes and there is nothing unusual or new running."

If the First Sentence is true one wonders how you know it will not restart if it can't be shut down. You are leaving something out here and need to be a bit more detailed so we can visualize your problem. (Pretend you are describing the problem to someone who can't be looking over your shoulder as you attempt to start or shut down the computer - because we can't)

Does the system shut down if you try using the Start button on the taskbar? If not what does it do? Does the system shut down if you press and hold the power button on the case? If not what does it do?

An alternate key combo for Task Manager is Ctrl + Shift + Esc -- have you tried shutting down the system from Task Manager?

What happens if you try Safe Mode?

What happens if you try the Last Known Good Configuration"?