Audiovox D1708 7-Inch Portable DVD Player
You get what you pay for.
I bought this unit at a warehouse store.  We have it strung up in the minivan for the kids to watch.  We too get the no disc message, but thats when we leave it in the van overnight in very cold weather (less than 45 degrees).  So, we pull it out everynight and pop it back in every morning.  It does what we need it to do.  If it breaks we'll buy something a little tougher to handle the temp extreme's.  Otherwise, it is 5 months in and still functioning.