My laptop frequently plays video as if in very low-color mode. Though the sound remains clear, it looks terrible, showing only a few shades of red, blue, or yellow. (It's even worse than 8-bit color.) The problem doesn't happen consistently, so I'm looking for troubleshooting advice or known solutions.

I use a Dell Latitude D620 laptop with Windows XP, on-board nVidia video chipset, Quicktime, and multiple monitors (laptop screen + VGA-connected LCD). Color problems happen in each application I tried, iTunes, a browser, and the Quicktime standalone player. It doesn't happen right after reboot, so could be from a sleep-wake cycle, or at least being on for an extended period.

Google results suggest reinstalling nVidia drivers, which I've done several times with no change. I have found 2 workarounds.

1. Reboot, sacrificing significant time and disrupting work
2. In nVidia control panel, change color to 16-bit, and then back to 32-bit

This happens with all video playback, so it's definitely not one corrupt file. I use workaround #2 consistently, but would love a longer-term solution.