My shipping module page has gone haywire!
I added a shipping zone allowing only the contiguous 48 states to the zenpwtable add-on shipping module, and now the shipping module page is all screwed up.

I'm running:

Zen Cart 1.3.9f
Patch: 1::
Database Patch Level: 1.3.9a

Now, when I click on Modules>Shipping all that show up are:
Modules Sort Order Action
Flat Rate flat 0
Free Shipping Options freeoptions
FREE SHIPPING! freeshipper 0
Per Item item 0
Per Unit

The buttons for editing, deleting, or installing modules are all gone.

When I try to go to checkout in the store, I get HTTP500 internal server error.

Any ideas?