Hi Jason - sorry for responding so slowly..
I'm not sure - I'm using the paypal link in the default checkout page.
Do I need to just make sure that the form for shipping info is filled out before clicking on the paypal link?
And yes - I've already updated the files with the support fix. Didn't help.
have you installed the "PowerStore 3: Support Fix - PayPal Express Checkout Failure" patch from the known issues section of the power store download page?