Hello TheOwl,

Actually I have found that past a certain point that poser goes in to what I call a waiting pattern.  It is still working on saving the files however if you try to view the status in Task Manager it shows up as Not Responding.  I just did a 2,600 frame BVH animation so that I could use it with another character and it took almost 15 minutes to save.
 
Best thing to do is have a cup of coffee and relax as sometimes poser just takes time.
Hope this helps