I installed 27.30 on my win98SE box that has a GeForce2 GTS. I edit the OpenGl settings in the display properties, click apply, and exit, but if I go back into display properties, the settings did not save. Enable Buffer Region extension, Allow dual planes... , and Use fast linear-mipmap-linear filtering won't save. Anyone had that happen?

I had that same problem. The bug is superficial.
Just keep clicking "OK" and go back to desktop.

Next time when you go to display properties, you will see that the new settings are enabled.

What I'm tring to do is disable them. It keeps re-enabling them when I exit display properties.

Hmmm ... I never tried disabling with 27.30, so I guess you'd better use 27.42 instead.