What suggestions could you make about a computer that reboots during playing movies? (It's not my computer.) It's a Abit motherboard, with a GF2.
Download the newest Detonator drivers from NVidia and make sure the program playing the videos is up-to-date (wether it's a gamn w/ videos, or it's WiMP, etc...). Also, make sure the *sound* drivers are ok, too. I assume these videos do have sound.
Other than that, send over some more info on the app, etc and I can make some more guesses...
Other suggestions: try the detanator drivers 30.x; The 40.x drivers are still considered "beta"
If it's Windows Media Player, you might try fuddling with the hardware acceleration features (i.e. turn it off) and see if that helps...
More info on your problem would be helpful...