Sorry that you are having some problems and are frustrated, that's no fun.

I am running P8 and P2010 on Windows 7 x64 bit with no hiccups what-so-ever. However I did have an issue simular to what you are experiencing I think with P7 and/or PoserPro (can't quite remember). If I had V3 loaded as a default figure and went to rotate her when Poser opened the system would freeze and crash. I tried loading another figure as the default (Simon) and could open Poser and rotate the figure with no crash...go figure. So that's what I did.

Now I am not saying that V3 is defective, but encouraging you to try possible another figure for trouble-shooting measures. If it's a certain figure that will crash your system, is it when you try and rotate the figure? Will Poser open without doing anything to the figure. Try just deleting the figure and loading a new figure...stuff like that. That's how I figured out a work-around.
Hope this helps.

Comitted to excellence through art.