Outlook Anywhere rejects correct login and writes Event 4625 in Security log

Hi,

I have an issue where one of our users cannot login to his Exchange account. He is connecting via Outlook Anywhere and using the correct credentials, but his login is refused.  In the security event log there are multiple event 4625 "an account failed to log on" errors.  An example is attached.  I have setup a test Outlook profile from another external location and that works fine for me.  When I deliberately enter the wrong credentials in my test environment the 4625 error looks different!  See Additional info below.

OS is SBS 2008.  Exchange 2007 SP 2 Roll-up 2.

Any suggestions welcome!

An account failed to log on.

Subject:
	Security ID:		NETWORK SERVICE
	Account Name:		SERVER$
	Account Domain:		MYDOMAIN
	Logon ID:		0x3e4

Logon Type:			8

Account For Which Logon Failed:
	Security ID:		NULL SID
	Account Name:		username_here
	Account Domain:		mydomain

Failure Information:
	Failure Reason:		Unknown user name or bad password.
	Status:			0xc000006d
	Sub Status:		0xc000006a

Process Information:
	Caller Process ID:	0x2718
	Caller Process Name:	C:\Windows\System32\inetsrv\w3wp.exe

Network Information:
	Workstation Name:	SERVER
	Source Network Address:	xxx.xxx.xxx.xxx
	Source Port:		50440

Detailed Authentication Information:
	Logon Process:		Advapi  
	Authentication Package:	Negotiate
	Transited Services:	-
	Package Name (NTLM only):	-
	Key Length:		0

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