Distributed transactions: ITransactionJoin error on two 2003 Servers

I'm hoping someone can help me, I am trying to start a distributed
transaction across a linked server. Both servers are Windows 2003 (pre
SP1) servers, and both are running SQL Server 2000 SP3a. I am getting
the following error message:
Server: Msg 7391, Level 16, State 1, Line 4
The operation could not be performed because the OLE DB provider
'SQLOLEDB' was unable to begin a distributed transaction.
[OLE/DB provider returned message: New transaction cannot enlist in the
specified transaction coordinator. ]
OLE DB error trace [OLE/DB Provider 'SQLOLEDB'
ITransactionJoin::JoinTransaction returned 0x8004d00a].
I have checked loads of KB articles, and other newsgroup answers and
have come up with the following ideas, all of which I've done on both
machines:
1. Enabled network DTC access on both machines
2. Ensured network and XA transactions are checked in security
configuration
3. Ensured DTC is running on both machines
4. Set the port ranges to 5000-5020 in COM Internet Services Properites
(although firewall is off)
5. Ensured both machines can ping each other by Netbios names
6. Turned off RPC Security on both machines (setting in registry)
7. Set on RPC and RPC Out in Linked server settings
8. Rebooted (many times) both machines
If anyone has any other ideas I can try (apart from changing the code,
as we have to do things this way, it's not all our code) then let me
know as I am pretty much stuck.
Thanks for your help!
Aron Cox,
Hampshire, UKI am working in the same problem. See KB839279. If you change
Transaction Manager Communication to "No Authentication Required" it
works but your not authenticating. I also read somewhere that changing
the account from Network Service to Local System, it may work.
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