This question may be related to a resolved thread.
I have a similar issue as the thread in the link above.
It seems that when a user does not type in the correct Captcha word the first time around they get sent to the error page that tells them
“The form you submitted contained the following errors:
You did not submit the word exactly as it appears in the image”
So when they click on the link (Return to Previous Page) to go back to the form, it takes them back to the registration form and the Captcha image does not change so when they type in that word once again, they get the same error message as above.
Could the issue be that when the user gets taken back to the registration form, from the link on the error page, the registration form does not refresh? and therefore the new Captcha images does not load?
If this is the case is there a way to have the registration page refresh when a user gets taken back to it from the error page, or have a load a new Captcha button?
I am currently using ExpressionEngine v 1.6.8.