I am running windows 7 64 bit as well, and have the exact same issue. Any time I select more than one unit, my game starts freezing, then hauls ass to catch up. I am however running the game via an ISO (I always run whatever game I'm playing on an ISO via my SSD, works the fastest) so it has nothing to do with the CD drive. It may be that I am running two monitors, but I'll look more into it and report my findings here. As it is, I can't even play d2k on vista/7 :( *edit* Two monitors isn't the issue, an update on drivers isn't correcting it, a different hard drive doesn't work either. The only possible thing I can see working is a virtual machine. I will report back on my findings there.
