Guest Checkout Errors, Cannot get passed authentication

[samhunt]

On my test site - http://5.79.1.99/ I've enabled the 5 step checkout and enabled guest checkout, the problem is when I try to checkout as a guest no matter what information I put in, it will always say "There is 1 error 1. email is required." even though the email field is filled in!

 

Hope someone can help, I've been trying to fix this for hours!

 

I'm using version 1.5.0.17

Edited November 11, 2012 by samhunt (see edit history)

[ruilong]

Check your rewrite settings, if you have duplicates for several languages (authentication) you can get this error on some versions of 1.5

 

(settings is located under preferences->meta)