I love DVDs, but I have had terrible problems with fragmenting and stalling with Cathe's stuff.  I have a Panasonic DVD player and have had no problems with any other fitness DVDs and no problems with theatrical DVDs.  I don't know what SNM is doing differently with their DVDs, but I wish they would check into this issue more deeply.  My Pure Strength and CTX DVDs played well, but I have had problems with most of the others.  I don't think they are defective, per se, but there are compatability issues.  I traded away my Rhythmic Step DVD and, when I had trader's remorse, I traded back for it, but I made sure I got it on VHS.  Cathe's DVDs have wonderful chaptering and options but they are just too problematic.