I also have the same problems you mention. Started just after the 12 months inital warranty had expired!! So couldn't exchange it. Have looked up about this DVD player and found lots of owners with lots of problems. So, my conclusion is that the SAMSUNG HTZ30 is not a good and durable DVD player.
I have a very cheap 8 year old DVD player which has been knocked around, dropped, dented and it still plays any DVD, VCD, DVR, CD or just about anything you ask it to play - even soiled and scratched DVD.
Samsung?? Never again.
Wizerureka
February 2010