My Vista system became nearly unresponsive a week ago.  I tried to alt-ctrl-del to bring up task manager to see what what hogging resources, but after several attempts nothing.  About 5 minutes later, I get a pop-up that states ‘Failure – security options, Logon process has failed to create the security options dialogue.”    At least it knew there was a problem. The only way to fix it was the 5-second power button hold.  Alas, XP was more stable for me..

Update: I have not gotten this error message again. It seems the shell has to be in pretty bad shape to present this error. I was taxing the system pretty hard at the time, and getting a better video card has seemed to fix most of these types of errors