User having trouble registering

[coopdad]

I have a user that is trying to register and every time he either goes through the automatic link or manually inputting his username and activation ID he gets this message:

"We could not activate your account because this web address is not valid. Make sure that you have the entire address from the email, and that your email client has not split the address over several lines.
Please try again with the full address from the email that you received. If it still does not work, try filling in the activation form:
Activation form..."

I am pretty sure the email address he used when registering is good as:
1. He got the "click here to finish registering" email.
2. I got email from it. And when I emailed it no bounce.
3. when a spammer tries to fake register with a bad (fake) email address, I receive a bounced error message and I did not see his show up.

Any ideas?
Thanks, John