Jumping/Too fast

I've tried the TGE 1.4 demo, and all throughout the FPS demo and car demo, I was lunging forward 3-4 seconds of walk/drive distance every couple seconds. Also, in playing some of the TGE based games such as shelled!, it will play fine for a while, but eventually it will be going super speed (about 5x normal speed) and won't stop. Is this an engine issue, or maybe an issue with my particular card? Granted, the card isn't the best one, but still.

Also, this does not happen at all with the TGEA demo.

my machine specs:
Processor: Athlon 64 X2 3800+
2GB RAM
GeForce 6200 128MB model

Edit: Ahh, I set the afinity of the demo and Shelled! to run on one CPU only, and the problem disappears. Odd.