I use an Apple TV2 with a US itunes account and have been happily watching movies for 2-3 months.
The last couple of days I have tried to watch two new release movies, "Harry Potter" and "The Way back". Both movies have got to about 20 minutes and refused to go any further. i have tried everything including a full restore of the ATV2 with no success.
My kids watched another new release movie the same day I tried to watch Harry Potter and it worked fine?
I have emailed Apple but doubt they will be much help as I am using a US account from NZ.