page not found, 404 on sign up

Hi,
out of about 50 signups only a small hand full seem to be getting an error message on page two of the signup process. I was finally able to duplicate this error myself on one of my computers. Happens every time I sign up with it.

how can I trouble shoot this if it is only happening to a very small few?
I am still not understanding what is causing this.

It is in IE 7 not sure about any others. But it is not IE 7 that is causing the problem. I have two other pc's with IE7 that work perfectly with no errors.

the url having this issues on the small hand fulls pc's is the same as the one on the pc's that work http://mydomainname.com/wamp/www/wp-signup.php

I noticed on the computers that it works fine on, I can go directly to the address as mentioned, but with my real domain name in place of mydomainname.com

but on the computer that I get an error message, The Page can not be found. I get this message even when I go directly to the url as above with my domain in place of mydomainname.com

and actually, this is an edit to this post.... I just tried going to the url in IE on the computer it works on, and notice that Page Not found is being added in the Title tag along with my normal title.

I also just tried to register normal, and on the second page, along with my normal title in the title tag I am seeing an addition of Page not found.

in fact after my title is this » Page not found</title>

Could this be what is causing the problem? if so is there a fix?

Thanks for any help you can give me with this.

Tony V