hmmm did I read that right and that you are creating and destorying pbuffers as you use them?
I'm not convinced thats the best way to go about it, each time you create you making a new context, its probably better to create a couple of contexts on startup and reuse them as needed (and pray a proper render-to-texture extension appears soon... )

yeah, you can free and recreate them as needed, however in a game situation its pretty safe just to reserve them up front and leave them around until you dont need them for a prolonged period or until the game ends [smile].

Granted, it is possible that the driver could well reclaim the pbuffer for some reason (most RTT code I've seen has a check to make sure the pbuffer is still alive), but i've never seen it happen and i dont know why it would (I guess it could happen if you create all your contexts, delete them and recreate them (say to change screen res) and dont indicate you have done so...