Sync issue with Exchange 2003

I have had my XDAII sync with Exchange 2003 over wireless GPRS for a few
months with no problems.
A few days ago I get a sync error on my XDA - Unable to sync with message
( subject of email message ).
I have hard reset the XDAII and wiped all data. I now get no errors but I
also don't get any email,contacts etc.
This has not fixed the problem and it appears to be an issue at the Exchange
end. Is there a GUID I can delete from the registry or an entry somewhere
that I can reset for my Exchange account?

Any ideas?

Thanks

Brian