I had a problem today where whenever a full backup of the master database was taken by Backup Exec the Service Broker would say in the SQL Server error logs:

Could not start Service Broker for database id

Google didn’t really know what was going on but I found that if you delete the master4IDR file on the offending server (probably in the default database directory) then do another few backups the problem vanishes.

master4IDR is a copy of the master database that is taken when Backup Exec backs up the database. It is used to do disaster recovery on the server.