I also experienced had a similar error while running SQL2005 SP2. We did receive an error 1067 when manually restarting it via the services snapin.

Turns out Microsoft dot net framework 2.0 was corrupted. This was only determined while trying to repair the SQL install and received a prompt regarding dot net 2.0. So we cancelled the SQL repair and instead repaired the .Net 2.0 installation. Rebooted and SQL agent started automatically. Hope this helps.

Regards,

-John