I have a Dell D630 with the NVIDIA chip that is having a display problem which I think may be different and am looking for some troubleshooting advice (it is out of warranty):

The display will start to fade from the bottom up or sometimes random horizontal lines will appear across the display.   When they happens the display is frozen.   Pushing down on the the top of sometimes the sides of the display will sometimes get the image back.  If I hook an external monitor up it works.  It appears this may also be heat related.   This does not seem to match the sample pictures I have seen of the NVIDIA problem.

For the record this is XP SP3 and the system does not crash when this happens.

So, is this another manifestation of the NVIDIA problem, a failing LCD, or something else?

Thanks.