Video Playback / Recording Devices

I recently rented several DVDs of Alias at the local video store. I was able to watch a couple of them, but then all of the sudden, they would no longer play. I tried several times and it would just attempt to read them with nothing actually happening and then it would either freeze up or spit the DVD back out. I thought it must be the discs, so I took them back and rented the the same ones from a different store and the same thing is happening. All other DVDs we try to play are working fine, so it doesn't seem to make any sense. Can you help me figure out what is going on?!

Okay, so I'm able to put a disk in, it will read and begin to play. I can get to the disk menu, when I hit play...it will play for a few moments then the tv screen will flash black, then snow, then black and the player will shut off. Now if I leave the menu screen on for too long ( around 3 minutes w/o selecting an option it too will flash then shut off.....can anyone help?

i have a memorex mvd2037 dvd/vcd/mp3/photo cd player.something happened when i was in the setup menu. now all get is sound there is no picture at all, and the setup menu won't come back up.