Oh, sorry, misread it as you not getting pop ups or notifications for PM's.
I have no idea whats going on then. On a simialr note, when anyone PM's me i get an email, which in turn is forwarded to my Blackberry. I have noticed that the emails seem to be coming through to my Blackberry a few hours after the PM. Assumed it was an issue between my inbox and the Blackberry, but if others are having the issue then i guess Sean will look into it when he gets some time.
That would probably have something to do with your BB, it's probably that's it's syncing is a bit dodgy of something, not the site