2Checkout Help!!!

Hi,

This is driving me bonkers, can't seem to find why this module is giving me such problems, been getting an error:

1364 Field 'return_md5' doesn't have a default value
in:
[INSERT INTO 2checkout . . .

When 2Checkout is selected as the payment method and I select continue.

Here is all the gory technical info:

Server Host: https://www.legacyengineer.com (72.80.182.86) Database Host: localhost (127.0.0.1)
Server OS: Windows NT LEGACY 5.2 build 3790 Database: MySQL 5.1.34-community
Server Date: 07/20/2009 00:09:22 Database Date: 07/20/2009 00:09:22
Server Up Time: HTTP Server: Microsoft-IIS/6.0
PHP Version: 5.2.9-2 (Zend: 2.2.0) PHP Memory Limit: 128M PHP Safe Mode: Off
PHP File Uploads: On Max Size: 2M POST Max Size: 8M
Database Data Size: 464 kB Database Index Size: 441 kB

the store is at https://www.legacyengineer.com/storefront

If anyone can give me any advice/suggestions, I'd really appreciate it, thank you.

Curt