I remember this being talked about recently, but I seem to be having the same problem still. Looking at a couple of previews last night, the loading would start, not make any progress, then dump me back to the movie screen (with the description of the movie and the option to play the preview).
This is somewhat sporadic. It happened with Morning Glory and I believer The Next Three Days. Other previews of new on dvd did work though. Thought maybe it was a problem with the server not responding at first so went back and the previews that didn't work before still didn't work.
Am I the only experiencing this, or has Flixster basically become worthless to others too? I'm not going to raise a stink about a free channel that just shows previews not working, but it was a nice way to check out what's going on in the movie world since I don't watch much commercial television and so miss the previews and whatnot I'd normally see there.