STEAM (older games trouble)

I recently got the dark forces 2 and quake 3 games with a collection purchase on STEAM, but all the games work except for these. They'll start up, and you can read the menus okay, but after the gameplay starts the screen goes all outta wack. It's as if the initial image drawn doesn't keep refreshing as things are your sight moves, so images blur all together. It's a difficult thing to explain. One other thing is that the video clips in dark forces 2 is a tiny box instead of full screen. It's funky because Dark Forces 1 works fantastic and everything is full screen, but the 2nd installment is fudged! Anyone have a work around this? Thanks!

Yes, it's a 40" LED/LCD samsung, 16:9, 1920x1080p tv/monitor using HDMI.

Turning off the User Account Control allowed Jedi Knight: DF2 to be playable, but shortly after getting into the bar the picture goes psycodellic with bright colors and eventually bombs. I started DF1 which was working fine before with UAC off and it eventually did the same effect but didn't bomb. I could hit escape and return to game and most the colors would restore, but by doing this again at some point the game would crash.

Doing the cache check under steam-game-properties turned out all okay.

Also, all my drivers are current, CCC10.3