Shipping Address Country Empty error

Ive already used this fix page in the past, im on 1.3.7 and just maybe thats why my site is getting problems since that change Zen is posting 1.3.8?
I have had two missed order using paypal & the errors are;
Response: array (
'TIMESTAMP' => '2009-01-15T18:08:09Z',
'CORRELATIONID' => '161aa2568a69d',
'ACK' => 'Failure',
'VERSION' => '2.3',
'BUILD' => '801690',
** 'L_ERRORCODE0' => '10731',**
** 'L_SHORTMESSAGE0' => 'Shipping Address Country Empty',
'L_LONGMESSAGE0' => 'The field Shipping Address Country is required',**
'L_SEVERITYCODE0' => 'Error',

Reading the error code, (is there a list of these somewhere?) and the empty field, where does the problem lie.
'SHIPTOSTATE' => '',
'SHIPTOZIP' => 'BN65 33J',
'SHIPTOCOUNTRY' => '',
The country field and state on this one was blank, but surely if the customer fields are *required how is it customers can avoid adding such important parts of addresses like the COUNTRY & a telephone number!
The previous entry was as follows;
[ship_city] => romey
[ship_state] =>
[ship_postal_code] => so91 77q
[ship_country_name] => United Kingdom
This one did NOT have United Kingdom missing but same error. State field empty though.

This topic had also been raised in this other thread, although its stopped before a definative answer seemed to have been posted.
I have now linked each to each other.

http://www.zen-cart.com/forum/showpost.php?p=670720

If you are having problems with this one go to this thread where its shows how to solve the issue.

http://www.zen-cart.com/forum/showthread.php?p=504386#post504386