I've been playing Half-Life Episode1 on my PC. I set the resolution to 1920X1080 & it looks awesome. Problem is, every so often a wave rolls up the scrren. What cuasing this? I'm playing on a Samsung 1080p DLP. I'm running the game with a 7800Gt GPU (just one). I would like to play at this res but if i can't fix this problem I'll have to go back to 1360X768. Thanks for all the help.