Have a TV set compatible with the PS3's Full RGB mode? Likely, you've experienced the issue where rebooting your PS3 actually resets the color settings - reverting back to the limited RGB output signal, even though you had previously selected Full RGB. A rather annoying problem indeed, but here's the good news: Sony plans to fix the issue with the release of firmware 1.81.
The news comes from a user over at the official PlayStation Europe forums, who called in Sony's support line asking for help with the problem. He says the update is due out by this Friday at the latest. There could be other bug fixes as well, but for now all we know is that the update will fix the color settings problem.