Editing the autoexec.cfg to have "MaxFps" "30" in addition changing the additional options to the following should fix it:
[X ] Disable DirectX 6 commands
[X] Enable optimized surfaces
[X] Enable poly gap fixing (slower)
[X] Enable triple buffering
You could choose "Always specify these command-line parameters" to help the game to force these options, even if you leave that particular field empty.