The rez gets locked when you start or load a game. Quit, then restart the program. Before you load a game or start a new one, go to your display options and change the resolution to whatever your hardware will work best at (what is your hardware, btw?). And what do you mean by graphics "flipping out"?
When I use the frame limiter, it helps out a lot. At 1600 x 1200 32-bit with Frame Limiter on, it's nice and smooth at 30fps. If I drop to 1024x768x16 and turn off Frame Limiter, it's a choppy 80-100. Very odd. Also, it didn't play nice with Vsync off, so I turned it on since it would never hit my refresh rate anyway.
Your results may vary greatly. I'm using an XP 1700+ @2.24 and a ti4200.
deadseasquirrel