You may get into this situation, when you configure your replication agents to log into the publisher and/or subscriber using "SQL Server authentication" (where you specify a specific SQL Server login, to connect to the publisher and/or subscriber). It will work fine initially, but when you change that particular login's password, you get the above mentioned errors. To solve this problem, whenever you change that particular login's password, make sure you change the password in the enabled publisher's and/or enabled subscriber's properties on that distribution server.
To change the publisher's properties:
- Open Enterprise Manager
- Connect to the Distribution server
- Go to Tools -> Replication -> Configure Publishing, Subscribers, and Distribution...
- Go to Publishers tab
- Click on the properties button (...) against the publisher's name
- Enter the new password for the SQL Server login.
To change the subscriber's properties, repeat the same steps as above, but in step 3, go to Subscribers tab.
Restart your agents, and they should be able to connect to the publisher/subscriber without any errors.