2006 gmc radio time reset problems

I have a 2006 GMC 2500 w/ am/fm single cd that returns to 12:00 every time the engine is started. Is there a simple solution or is this a complicated issue?
Check all your fuses with a test light. There is one that is for keeping the memory only and it's probably burned out assuming this is a factory setup. 

This is a factory Radio, the only thing that makes me think it is not a fuse is that it used to do it occasionaly.
A blown fuse would have always caused it like it does now, but that wouldn't explain the occasional part. Any Ideas??
Well I don't diagnose too many of these but you will have 2 power sources. Constant power for the memory & clock which will be a low enough source as no to give you a drain and then switched power for all the other functions of the deck.

If this is a intermittent problem the odds are high it's an internal problem with the deck. About the only thing you could do to verify this would be to hook up a meter or scope to the power & ground sources to see if you are losing anything when the problem occurs, if not then the problem is in the deck......