I removed the patch from 27th June 2009, PCI Scans - (patch to handle low-priority warnings on search screen causing scan fail)
/includes/extra_configures/pci_patch_v13x_search.php

http://www.zen-cart.com/forum/showthread.php?t=130701

As soon as I did, the Captcha again resumed working 100%.

I do want the added protection of the patch that keeps certain error messages from appearing and revealing too much, but I also need the Catchpa functionality.

Any solution to this???