I use this dream too, and I find that any of the Dynamic Dreams (Dreams that you can manipulate in some sort or manner), can be finiki when they restart after they've been paused in some state or other for what ever reason.
If I have a dynamic dream (Photo Collage, Liquid Dream, Winter Snow... these dreams are dynamic, some kind of interaction between you and the dream) running for instance I start a game (Joint Operations, Unreal Tourniment or any other games) that uses Direct X that sometimes the Dream needs a little coaxing to restart.
So I'm betting this has something to do more with Direct X Issue then it has anything to do with the Dreams and Direct X's ability to drop the connection to the dream and then reconnect the dream afterwards.