End Task on Hung / Not responding programs does nothing!

Is anyone else having the issue where sometimes when a program will hang (either a 3rd party like mozilla firefox/Thunderbird or explorer.exe) clicking end task does nothing at all?  It is very VERY frustrating.  Additionally, when this happens, you are forced to turn off your computer by holding down the power button, because it will never complete the shutdown sequence.  I should also note that taskkill /f does NOTHING but reports "success" when you attempt to kill a a program.  At the time of this posting, explorer.exe has two instances open in task manager, neither of which I am able to kill with end task, or right click and end process or process tree (although the child programs they spawned that WERE responding when end process was pressed will close).

This problem occurred in vista as well, but it seems substantially worse in windows 7.  I am at a loss, and will have to stop using the OS altogether.  I recognize that it could be a driver malfunctioning or something, but the operating system NEEDS to allow you to kill unresponsive processes.  explorer.exe has now been stalled and hung for 48 minutes without doing ANYTHING.

If this is the wrong sub forum to place this in, please tell me and I will repost in another.

Any reply on this would be useful, this problem is about as bad as it can possibly get for an operating system.  I am now pressing/holding the power button to shut down.  How useless.