iPhone gets event 3005 Activesync error with SBS 2003

I have a Microsoft Windows 2003 Small Business Server that has been communicating with all of my IOS devices for months and now one of the iPhones get an Activesync error when trying to access Exchange mail. I get an event 3005 -

Unexpected Exchange mailbox server error.

Verify that the Exchange Mailbox server is working correctly.

I have other iPhones and iPads that are accessing the server correctly and when I setup the same user on different iPhones they are able to access the accoutn for the user accountthat is having the problem which means the issue is something on the phone.

We took the phone to AT&T and had them reset it. We then setup the Exchange account again and it worked for about a minute and then started the same errors.

Does anyone have any ideas?