[X4U] Monitor problem or Video card problem?

[Ed Gould]

I have a G5 Dual 2.67 ghtz with 6 GIG of memory and a Cinama HD  
display (30 inches). Also a Radeon 9650 with 256MB
I am running 10.4.11
I have noticed after reboot(sometines) that the deck top is empty no  
drives no NOTHING, this does not happen all the time.
To fix the issue my friend changes the display from 1280 X 800 to  
1034  x 768 and wait for 15 seconds and all of a sudden the desk top  
re-appears.

This started say in the last month. Can anyone explain this happening  
and could the Radeon card be going bad?

Ed