Double queue reader or is it still busy?
Solved it. 

The Queue Reader agent is only used in snapshot or updatable transactional replications.

I just deleted the job and emptied tables MSqreader_agents &amp; MSqreader_history from the distribution database. Finally I killed the qrdrsvc.exe process.

Helpful links:
http://social.msdn.microsoft.com/Forums/en-US/a6de412b-ebae-4a39-b00f-8f724237e14e/queue-reader-agent-error
http://technet.microsoft.com/en-us/library/ms147378.aspx