Strangely enough I had the same issue. Try a small test with another output format, say wmv. Their FAQ about it being a VISTA problem is certainly not complete. Am just trying out the product, converting flv to avi. I am running XP Pro. The issue turned out to be Prism did not like the avi codec - here's what I did, first try the same conversion to wmv that worked fine, so I knew it was not an issue of not having access rights to a particular location. Swapped the codec to a different one (encoder options button next to the output format selector), worked better but then crashed. Restarted Prism, it asked if it had just crashed (very interesting if not psychic). I said yes and Prism offered to switch to its own codec set. I said yes. Now on my second test looking good. Sorry I can't check the settings right now. In middle of long test.