d255 screen shake

hi to everyone!!

just bought a d255 and its been working great!, my problem lies when i connect it to my true hd lcd tv! the best way i can explain it is if i continue to browse the net there isn't a problem/watch a movie. when i leave the screen stagnant for a while or even watch tv, when i come back to the monitor (pc mode) the screen is going crazy in which i can't stop! if i unplug the d-sub lead for a while, then plug it back in it goes ok again or as soon as i shut down the pc the tv instantly stops shaking until it shuts down. the lcd screen of the netbook doesnt have a problem.

its only 3 days old and a little concerned. any help would be great