Having problems with registration on checkout page

[edudflog]

VM ver 2.0.18a
Joomla ver 2.5.9

On checkout, cannot register.  Keep getting the message "The solution of task you submitted was incorrect. Please read the instruction and try again."  I've disabled Captcha and turned it off in Virtuemart.  Still getting this message.  I am reluctent to upgrade the version as each time I do, it breaks my site.  Happened 3 times.  The home page registration link and form work fine.

Your help would be appreciated.

Site name: novelocket.com

Thanks

[GJC Web Design]

that message comes from key captcha so it must be enabled some where

[edudflog]

Thanks for your assistance - you were exactly right and disabling the plug-in eliminated the message.