1054 Unknown column 'zen_order_id' in 'where clause'

[DrByte]

I can go in and edit any order not payed with via PayPal, however I get the above error on all PayPal orders.

...

I just did a test order via PayPal and the order process works fine.

It doesn't make sense that you can place an order via PayPal without error, but cannot edit/view the order details via the admin ... unless you have installed a 1.3.8 PayPal module somewhere, or have altered the database in some way.

Anyway, you seem to believe that none of that has happened, so just go and manually fudge your database back to the old format and pray that everything else is fine. I DO NOT RECOMMEND THIS APPROACH, because I believe something else is wrong, but this is a bandage you can try at your own risk.

ALTER TABLE paypal CHANGE order_id  zen_order_id int(11) unsigned NOT NULL default '0';

If that doesn't solve it, delete your database and your Zen Cart install, and start over from scratch.

You might consider installing v1.3.8 instead, since 1.3.7 is more than a year old.