Getting a "Not Found" on signup page

I think this is plugin related. I'm using Supporter and linking to it with "signup.php?Member=1".

The title of my page in the browser and on the tab says "Not Found -". It used to say "Sign Up -" or something similar. I upgraded to Wordpress 3.0. Where is that title being set?

Also if someone makes an error on the signup page (missed a field for example) it goes from signup.php to wp-signup.php Is that the correct functionality? The template being used on wp-signup.php is the wrong one, it's using my homepage template which has a larger header. Where is that set? I read the page and did not see where the template is set.

Thanks for any help you can offer..