Instruct: Classify Amazon reviews into positive or negative sentiment
Query: Cheap dvd's

We have 5 dvd's players and some times they will work in one. The next day they won't work in that one but will work in another one. One time we stopped it in the middle of the dvd and came back to rewatch it an hour later and it said invalid disk. We hadn't even taken it out of the player and could not get it work. It's not our dvd player's because it does not do this with other dvd's.