Power-off

[Sponger]

Hey folks,

I have had fedora installed on my system for a coupl 
weeks now and lately when I shut down, the computer 
does not power down, after all proccesses have been 
killed and the term signal was sent.

Any ideas?  I have not changed, added, or modified 
any hardware on the system.  It is a DFI lanparty 
nfII ultra, with a 2600+ "Barton" amd, 1gb crucial 
pc2700 ram, MSI fx5600.

Thanks guys!