I have a similar problem on and off with Poser 6. I have tried deleting preferences, reinstalling on a new hard drive, nada works. Also a clean boot got it going for awhile, but now it's freezing again and I'm in the middle of a project! It opens a PZZ, lets me look at it, but if I want to delete or change anything, the dialog box freezes up, goes gray or the mouse pointer disappears and I have to control-alt-delete shut it down.
I even upgraded my RAM & graphics card with no dif.
<:^(