Why does error 500 occur when reactivating my online store?

[bnybo]

I am trying to reactivate my store.  It walks me through a "Choose a Plan" screen.  Once chosen, I select my payment option and enter my zip code.  When I click "subscribe" I get a "leaving page" popup box.  If I click on the red "Leave" button it throws an error 500 and the whole thing starts again.

I have tried different browsers and even different machines ... same result.  I am hoping you can fix this one on your end.

Thank you!

UPDATE: I was finally able to do it with my phone, but it still loops on the PC.