Quake II, Athlon 750, Elsa Synergy II

Having a little problem with Quake II locking up. My PC is an Athlon 750, 128 mb RAM, with an Elsa Synergy II under Windows NT 4.0 sp5. Quake II locks up during play. Sometimes, it locks up the entire system. Usually though, I can ctl-alt-del out of it. Occassionally it just locks up for a few seconds. I do notice that triangular artifacts seem to appear just before the lockup. The documentation mentions that the Synergy II is optimized for the PIII chip (using SIMD instructions). Supposedly, the Athlon supports this. Any ideas?