Ok, this is going to sound strange, but for those of you having strange problems with poser under any version of windows, try this:

First, open your C drive (or whatever drive you have the poser app on) and schedule a disk check with automatic fix selected.  Reboot your machine and checkdisk will run.  This will take a while, but it will make certain that all of your files are properly indexed and no crosslinks exist.

Then, defragment the harddrive in question.  Now, why would this possibly make any difference?  Because Poser, wonderful application that it is, is probably the biggest memory hog on the planet.  As a result it makes very extensive use of Windows virtual memory, which in reality is nothing more than a swap file written out to the drive.

If this swap file becomes in any way corrupted, or is so fragemented that it becomes difficult for windows to access it in a timely fashion, Poser starts behaving erratically.

Very strange, but also very true.  Most other apps don't seem to mind one bit, but for whatever reason Poser is very, very sensitive to this.  So try a disk check followed by a defrag, and odds are pretty good that it will fix a lot of your stability problems regardless of what windows version you run.

Oh, and I run Poser 7 under Windows Vista 64, seems to work fine for me provided I defragement the drive once a week, runs nice and stable with no problems whatsoever.

-Never fear, RenderDog is near!  Oh wait, is that a chew toy?  Yup. ok, nevermind.. go back to fearing...