OS X not logging off, restarting or shutting down.

[PSUstoekl]

I'm having a fairly simple yet infuriating problem... whenever I go to log off my user, restart the system or shut it down, my desktop magically reappears, as if the restart has already occurred.

What's the cause of this, and how can it be corrected? Thanks in advance

 

[mad jew]

What sort of machine do you have and what is the OS? Have you tried pulling the power?