HELP!!

Hi.

I've been having very serious problem with my
"Ati 3d Rage LT Pro", the last day i "correctly" installed windows NT 4.0 I downloaded the drivers for NT at ati support page.
Everything was great, but now i have realized that:

* I cant get my resolution better than 75 Hz, so now i cant use truecolor.

* My NT operative system is EXTREMEALY fragile. I cant work with my computer without a crash every 2 minutes, when the blue crash report appears it make atidrives responsible for the crash everytime.

I desesperately need an answer, Im using a Pentium II 450, 12 GB, 128 mb RAM.

Thanks for your time.