New users can checkout but existing users can not.

Hi All

This ones been bugging me for a few days. Not sure how long it has been occurring as customer just brought to my attention last week.
I had OC 1.5.5.1 and have upgraded to 1.5.6 version as well as upgraded the template to 1.5.6 version to rule that out.
Upgraded vqmod to 2.4.1. Ran install again.

A new user can checkout but existing user can not.
When click continue on the use Bill details section use existing address get the following.
I have UG the Vqmod but that mad

invalid syntax error.
Logged error.
2013-08-17 18:29:56 - PHP Notice: Undefined index: company_id_display in /home/content/05/6995005/html/opencart/catalog/controller/checkout/payment_address.php on line 144
2013-08-17 18:29:56 - PHP Notice: Undefined index: tax_id_display in /home/content/05/6995005/html/opencart/catalog/controller/checkout/payment_address.php on line 149

i have the same problem with 1.5.6 fresh install, default theme. Anybody please help.