Error in Direct Push Technology setup on MS Exchange Server 2003

Hi,

Can anyone help me troubleshoot my problem?

I am always having this HTTP 500 problem of setting up Direct Push Technology (DPT) among users on our Exchange Server 2003. 

Here are some hardware background information:

Front-end server:

Exchange 2003 SP2 with Windows Server 2003.

Back-End Server:

Exchange 2003 SP2 with Windows Server 2003.

I have tried doing what the following articles say but they were not useful: 

1. Deleting and recreating Microsoft-Server-ActiveSync in IIS
 

• http://hardware.mcse.ms/archive35-2005-12-262517.html

2. Problems in Synchronizing a Pocket PC with Exchange Server 2003 when using SSL and Forms-Based Authentication in OWA

• https://www.petri.com/problems_with_forms_based_authentication_and_ssl_in_activesync

3. How did we set up our Exchange for OWA, OMA, ActiveSync and RPC over HTTPS

• http://www.howtonetworking.com/email/oma1.htm

The exact event ID error still occurs:

Event Type:      Error
Event Source:  Server ActiveSync
Event Category: None
Event ID:      3005
Date:            3/21/2006
Time:           10:02:53 AM
User:            XXXYYY
Computer:   FRONT-END

Description:

Unexpected Exchange mailbox Server error: Server: [XXX.XXX.XXX] User: [[email protected]] HTTP status code: [400]. Verify that the Exchange mailbox Server is working correctly. 

This issue has been discussed before but no solution has been offered. I am almost compelled to call Microsoft to get my money back but I am hoping someone from this site can give us an 'end-all solution' to this problem. 

Thank you very much!