With PowerDVD 10 I have this DVD issue and I think it's because of disks being in less than perfect condition (I haven't noticed it on brand new disks). It will be playing smoothly, and then suddenly it will hitch (I assume this is when it hit's an imperfection in the disk), and from then on the video will be horribly 'juddery' like a slideshow. This will continue indefinitely, but when I manually seek back to a second or so after the frame that initiated the judder, it will play perfectly. WMP can play the same disk with no issue at all, and I never noticed this on PDVD8.