Anyone else have this issue come up?

I made a "create new account" form and then once a person creates their account they're brought to a login page so they can login with their newly created account. When I test it on my local system, it's fine. When I test it on the production server (over the internet), it's fine, but when the lovely client tests it over their internet account, there's a five minute delay between when they create the account and when they're able to login. If they try any sooner, they get a message that the account doesn't exist.

Is there some wierd time lag over the internet that applies to MySQL but not to the PHP/HTML on the very same page? I talked my client through this step-by-step over the phone and we used the same exact setup, so I know it's not their non-tech-saviness that's causing this.

Not a critical thing, just curious if anyone else has run into or knows of this strange effect. I just put up a notice saying, "thanks for creating an account, if you can't log in, please try again in five minutes."

- Julian