XPS 430 with ATI Radeon 3650 and S2009WB Monitor! Help

I bought this computer at Best buy and when I brought it home and started it, it worked fine, but when I set up my photo screen saver the screen goes blank and I have to manuelly shut it down because it will not let me use the Ctl Alt Delete method. Not only this my kids play Toon town online and when they go to login the screen does the same thing.

I took it back to best buy to let then look at it and they said that the game is not compatible, ok i can believe this but they said I needed to change the size of the pics to get my screen saver to work. Did that and it is doing the same thing. So my question is am I doing something wrong or is there something wrong with the monitor or graphic card?