One of peerflix's problems come from the fact that they don't easily distinguish between a movie you have but are not yet ready to send out (because you haven't watched it, or watched all the special features you want) and a movie that is ready to go at any time. So they may mark a movie as available but in fact nobody is ready to send it, and you don't get it.

I presume once you get a movie it is marked as in your collection but probably not queued up first thing (even if you watch it the night you get it.)