Ok, I think I misunderstood you with the 2 frames. So it is always 5 to 7 frames. And the numbers look good. Sorry, but I can't think of any other reason for your problem right now.
The only thing you might do is to try if you get the same problem with ordinary panel digitis. If you do, it's not related, to the progressbar. If you don't, it most propably is.
Oh, and just to make sure: You called LBGUI_open(), right?
