I'm not sure what stability issues people have had with Poser 8.  Poser 8 has been by far the absolute most stable version of Poser I have ever worked with.

As a matter of fact, the only thing I've never liked about Poser 8 is its incompatibility with fire walls.  Drives me crazy that my firewalls can mess with a program that doesn't even need the internet to function.  It's also been very, very difficult to make firewalls accept it for some reason and has been a source of great frustration.

Other than that though Poser 8 is probably the first version of Poser where they actually tried to pull the program out of the dark ages and they did it quite successfully.