Agent Security doesn't appear in Transaction Replication

Sorry if my English isn't good
I have 2 servers
Server A - SQL Server 2000 SP4 Enterprise Edition
Server B - SQL Server 2005 SP3 Enterprise Edition
Server A : Publisher + Local Distrbutor
Server B : Subcriber
When I set up Transaction Replication, it works. But after 2 weeks, when I reinstall, it has error.
At Creating Publication Step, after "Specify when to run the Snapshot Agent", it goes to Finished Step."Agent Security" Step doesn't appear.
So I can't configure username and password to connect to Subcriber.Finally, when I start replicating, it doesn't work.
Error is " Login failed for user 'NT AUTHORITYANONYMOUS LOGON'. Cannnot connect to Subcribers."
How can I fix that ? It worked, but now it doesn't. There must be someone's changed something but I don't know what has been changed ?
Thanks for helping

Thanks for reply.
I've read the link you show. His problem 's different with mine.
The error we got are the same. But in his situation, he had alias in Publisher itself. I didn't have.
In my situation , the Agent Security step doesn't appear. So when Publisher connected to the Subcribers, I wonder which account Publisher used ?
Seem someone configured the agent process run under Windows authentication ? If so, what I have to do ?
I setup Replication between Server C and B, it worked, but C with A it failed. Seem the problem's in the server A.
Thanks for reply