Laptop S-video in Black & White

One of my media computers is connected to one of our TVs via s-video -> RCA. This has proven to be a right fine solution and even though it's a rather old machine (P4, 512Mb RAM) it's proven sufficiently powerful to play 720p content over the network. Unfortunately for some reason outside my control it recently began only displaying video in black and white on the s-video port. I did some preliminary research on Google and found all kinds of weird and incorrect answers.

In the end it turns out the video output had been set for PAL color instead of NTSC. The actual fix for this will vary by graphics chipset so I won't go into much detail here, but just in case someone else is wondering why their s-video output switches to black and white: check the color encoding!