When you say it gets to 1/4 of the buffering bar "and that's it", what happens at that point? Does it freeze with the buffering stopped at that point? Or does it exit back to the springboard screen? If you send me a PM with your serial number I can see if I can find any clues.
I'm having this exact same problem. Everything streams OK except for Netflix. When I add something to my Instant Queue and try to watch it on my Roku player, I get 4 dots for quality and the buffering bar goes about 25 percent of the way across the screen before the whole thing seems to crash. It boots me back to the previous screen with information about the movie on it. Every time I try to view the movie it just boots me right out after the buffering bar progresses a bit.
Mark, I'm going to send you a PM with my serial number. Hopefully this is OK