Screen lock changes screen resolution
 

Whenever my screen is locked for an extended period of time it shuts off due to power management. This is not a problem in and of itself, but whenever I unlock the screen my desktop resolution gets all screwy and I have to change to 800x600 then back to 1024x768 to get it back to normal.

I am running mandrake 10 on a toshiba 2410 laptop and I have no idea how to fix this. Can anyone shed any light on why this problem is happening and how to fix it?