Certain runs of Samsung LCDs were built with power supplies whose capacitors go bad. One manifestation of this is red spots/purple spots after a cold start. If you own a LNT or LN..A model Sammy, do yourself a favor and inspect your power supply board. The industry as a whole has considerable issues with crummy capacitors. Ask anyone with an LG 50" DVR-equipped plasma.
Couple of bucks worth of capacitors, you're right as rain.