SecurityService can't be unregistered

CRM system works pretty fine before i install the Messenger 5.1. the
situation is that the security serivce can't start any more and when i was
trying to uninstall the CRM system, a error message came out saying
"SecurityService can't be unregistered" and also, the deployment manager can
not find out the nodes used to be under deplyment manager.
can anyone teacher me how to solve this problem? and why this happened?