Apple Support Discussions user "irfanhab" reports:
"I use a DVI to S-Video adaptor (bought from Apple Store) to connect my macbook pro (Feb 2008 model) to a Digital TV. Every time I connected it used to work fine and I could instantly play movies. However in Snow leopard, every time I connect the TV display is Black and White, and I have to restart my macbook pro, while the DVI to S-Video thing is connect to get a coloured screen."
Users can attempt to reset the display detection by navigating to System Preferences > Displays and clicking on Detect Displays. Users also report, as "irfanhab" has, that restarting their Mac with all components plugged in will result in the color screen as expected. Though there does not appear to be an official fix for this issue, Apple has already seeded Snow Leopard's first update, 10.6.1, to developers--an update that could repair this broken functionality. Stay tuned to MacFixIt and we will let you know!