"RunDLL32.exe" seems to support most applications (.exe) that use an applications extension (.dll). RunDLL32.exe should stop when you close all applications. I would guess that the reason you can't shut down is that RunDLL32.exe hasn't stopped as it should. You can confirm this by doing your Ctrl/Alt/Del routine before you shut down. If it is running, stop it first and then try shutting down normally.
Having done that, see if you can identify which Application you have just been running that may have caused the problem. It may be an old Legacy App that is trying to use the wrong .dll.
Try un-installing that App and then re-installing it.
Yes you can stop it as long as there are no applications running. When it is needed, it will start again.
An MCSE may give you a more informed answer.
[ 09 December 2001: Message edited by: fobotcso ]