From Ken Frenchypants, in response to Olson’s Tack issues with PCC & verifone:
there is a problem with verifone units in general with V8, if you hit cancel on the retail pro screen it will lock up retail pro unless you hit the red cancel button on the pinpad, this is logged and supposed to be addressed in the next core. (hopefully end of may) as long as you NEVER press the cancel button on the retail pro screen once a card is swiped you wont run into the issue.