Well, 10.6.3 has a lot of graphics issues and bugs.

for me, whenever i am playing a game, and i just go to windowed mode to check e-mail or something, and then i go back again to full screen mode, the screen goes pink, and i don't know why. even I degraded to 10.6.2, the issuse went away.

Just wait for 10.6.4, or downgrade to 10.6.2