2 different version 10.04

[John R. Sowden]

I downloaded an iso from the Ubuntu site and upgraded a computer via the 
Ubuntu  update program.  The upgrade has a picture of a terminal as the "log 
out " logo, the cd has the On/Off symbol.  The cd does not turn off the 
computer.  When I click to shut down, the 'are you sure' window pops up, but 
only sometimes does it actually shut off the computer.  I am always able to 
'sudo halt' from a terminal, after the former failed, and it shuts down 
properly.  Thoughts? 

John Sowden