What program does he use to play dvds?
InterDVD suggests an upgrade of the graphics drivers:
Download and install all drivers related to WinDVD, AGP, and your graphics or video card. After all drivers and software have been updated, test again to see if the error still occurs.
If the driver updates do not resolve the error message, then change the screen resolution to a different setting. To do this, follow the procedures below.
Right-click any open area on the Windows desktop and select Properties.
Click the Settings tab.
Change the color setting to 32-bit, the Screen area to 1024 x 768, and then click OK.
Google the exact error message in quotation marks and see what you can find.