Intel has confirmed that it is a problem with their driver for the
82915G/GV/910GL Express Chipset Family of display adapters. They say
that they will address the problem in a new release of the driver.

If anyone having this problem will email me the service tag for your
PC, we can demonstrate clearly to Dell that the problem is occurring on
many PCs (I have an open incident with Dell regarding this issue).
Reducing the graphics acceleration a level below that which DirectX
uses is a temporary workaround.

Thanks for your help!

Ann