I'm opening an IGES file that is rather complex (95,000 entities). MOI does open it (pre-set the surface and trim curve values from 10 to 20) if I zoom a viewport it gets to a certain point, stops, and the system is nearly hung. CPUs (it apparently isn't multi-cpu aware?) go to 68/65 and stay there. Getting to the Task Manager can be done but each screen update takes 10-30 seconds while drawing the window, buttons, text, menu bar & sub-menus over and over. It's interesting to watch the UI draw itself (never seen it in slow motion before) but after 20+ minutes, I enabled the fickle finger of fate and rebooted. I was using the /3GB switch, so started without it. No difference. Next time, I opened the model and immediately saved as a 3dm. No difference. Next time, I set CPU affinity to CPU1 only. The model zoomed out a little faster but stopped at a point not as far out then hung. Next time, I set the two values above to 30. Model loaded faster and I sequentially zoomed three viewports a little bit at a time each. One got about to the same point and hung the app.

XP32/SP2
2GB RAM
Dual AMD 2800+ MP-M
ASUS A7M266-D
PNY 6800GT 256 AGP 91.85 drivers