Suggestions I've tried are:
Move Poser out of the "Program Files" file.
Change the compatibility on both the poser.exe and the ffrender.exe and in that same panel choose “disable visual themes” and “disable desktop composition”.    

Since doing that my poser works a bit better than it did before and my problems were mainly the render freezing up at the end.  I still have a hard time with it freezing when I try to delete anything and I often have better results if I render from the "render settings" panel.  

Good luck, I hate Vista.

...... Kendra