Screen flickering

My Vostro 1310 (Should add that it has the 8400m GS) has a problem outputting an image to an external monitor. I've tried multiple different drivers to the same effect. The monitor (Samsung 216BW works fine connected to my desktop) so I'm narrowing it down to a hardware problem.

The problem is that it seems like the refresh rate isn't REALLY at 60hz. Its like its running at 55hz or something, so there is constant flickering on the monitor. Theres like bands running up and down the monitor. This is extremely annoying, and can't be good for the life of my monitor either.

Has anyone else had this problem before?

 

FOUND THE PROBLEM. it WAS a hardware problem after all, but not related to the video card. Instead, it was the power adapter giving the computer "dirty power". whenever it was plugged in, the lines would show up. On battery, they're gone. Gonna have to ring up dell to talk about this.