I just got a new computer with XP Pro (64) and tried Poser on it a few times last night and didn't have any problems.

Are you sure you have SR3 patch installed for Poser 6?  I installed SR2 and then SR3 as I didn't know if I needed both.

Also, perhaps try uninstalling Poser and then reinstalling it again along with both SR patches. See if that helps.  Other than that I don't really know what to suggest.

"It is good to see ourselves as others see us. Try as we may, we are never
able to know ourselves fully as we are, especially the evil side of us.
This we can do only if we are not angry with our critics but will take in good
heart whatever they might have to say." - Ghandi