Current > Cannot create a new user

1. Go to join page and enter all required fields.
2. Click submit.
3. Error message is presented on page that says "This account already exists", however the error message appears within the page, not as a popup, and with the wrong style. Also, the message is incorrect, as there is no user found when I search for the name.

I found this bug when trying to confirm that the registration macro worked when inserted into an Adwords page (http://current.dev.curriki.org/xwiki/bin/view/Main/AdWordswithRegistration?xpage=popup) and again when it is styled (http://current.dev.curriki.org/xwiki/bin/view/Main/AdWordswithRegistrationTest?xpage=popup). I get the same error on each version of the page, including the regular join page.

I saw this issue before during the Join project; refer to http://jira.xwiki.org/jira/browse/CURRIKI-4658 and http://jira.xwiki.org/jira/browse/CURRIKI-4660

This issue only occurs on Current, does not exist on Production or Beta. I'm using FF3.5 for Vista.