I havent played in a few weeks, but I was going at it pretty heavily from september-january. I usually got a lockup once every couple days. What I noticed is that it would lock up only if I had not rebooted my system for a day or two. If my computer had been running for 1-2 days straight, it would often lockup when I clicked on the D2 icon...then I would reboot & all was well. Actually, D2 is the ONLY thing that ever freezes up my machine, so I would imagine there is some sort of conflict originating in the game.
My D2 Setup:
P3 600/876
P3V4X
2x128MB Mushkin Rev.2
Geforce 256
Toshiba DVD, HP 9310 CDRW
Windows ME