SW2008 Backround goes black

While working on Solidworks 2008, my background turn blacksuddenly, the drawing still remains unchanged, even when i'm busyworking on the model itself aswell, the model keeps it's coloursbut the background just turns black for no reason.

After a few minutes it causes my whole Workstation to freez up, somuch that not even the mouse or keybaord responds.

What could be wrong

Dell Precision 490
I'm running Windows XP Pro (32BIT) updated to SP3
Solidworks 2008 (SP4)
4Gig RAM
ATI Fire GL V7350 (used latest solidworks reccomended drivers)

can anybody please shine a light on my problem.

Thanks in advanceSolidworksAdministration