SQL Server Service Manager feels like ages ago. All I can remember is you do get some type of flashing every however many seconds as it polls the services. I'd check and make sure all the services are running that it is checking.
Error 50000 is for user defined raiserror without specifying a message id - those just default to 50000. I'd probably check if the stored procedure sp_HLAutoStartSQLAgent to see if it could be coming from that.

Sue