Feneris - unfortunately that sounds like quite a sound diagnosis from dell. It doesn't sound software related, so it's then a question about which bit of hardware. If it was just the screen that was randomly knackering, then it would be odd if it *happened* to un-knacker itself when you did the Fn Suspend keypress... somewhere in between lies the graphics card, and so that would make sense to me.
You could try plugging an external monitor in and seeing if it exhibited any strange behaviour.
NW3