Please help Problem with Rega P3 belt "rolling".

So this past week I treated myself to a brand new Dynavector 10x5 cartridge and a new belt. Now the belt "rolls" and every few rotations snaps back into place causing an audible pop. It isn't slipping but rolling. It actually moves up the rotating spindle slowly then all of a sudden jumps lower causing the pop. The shop where I got this from has never heard of this and I even went to another shop with the belt to see if I could recreate the act there to no avail. This rules out the belt so I'm at a loss. Anyone? I was going to have a few friends over tomorrow for a listening session but this changes eveything.
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Does the belt also climb the side of the platter? If so, I would suspect that the spindle and platter are not level in the same plane. Just a guess.
The belt doesn't touch the platter on a Rega. It revolves around the platter support/spindle.
Are you sure the platter is seated correctly? It may be sitting a little higher than it should-a fraction of an inch will cause the belt to climb.
can you post a picture of how the belt is seated on motor pulley and subplatter?

for 33.3 it should be in the top groove of the motor pulley.
is the motor pulley shaft bent or dirty? you can clean the pulley with isopropyl alcohol.
The pulley maybe a little sticky, clean with q-tip and alcohol, put a little powder on the belt as a second fix, the Rega motor is held by rubber straps if they have moved much this could put the motor out of alignment with the platter
Is the small pulley on the motor shaft moving up and down? On Regas, I know this pulley can sometime come loose and needs to be reglued to the motor shaft.