I recently rented Shrek and it froze up many times and pixelized a lot. Earlier posts suggest that this is caused by smudging on the disc itself. When I asked a friend about this, he said that there was dust or contamination in the player. Could this be the cause, and if so how would I clean the dvd player? Also, I played the disc in my DVD drive on my computer and it played fine. Is there something different about a drive that allows it to read better? Thanks.