The Management Server was unable to obtain an exclusive lock on the Registry.
This can happen when another Management Server is also attempting to install the agent or when anti-virus or other spyware detection software has locked the registry for its scan or quarantine feature.
Ensure that only one Management Server is attempting to remotely install the agent. If you are sure that there is only one server that is pushing an agent, temporarily add an exclusion to your anti-virus software or spyware software to exclude the MOMAgentInstaller.exe process during the installation.