If you get the message: "System error 5 has occured. Access is denied." when you are trying to stop a service in Windows Vista or Windows 7 using the command prompt. This means that you do not have admin privledges.

In order to get around this, close out of the command prompt. Then right click on the cmd.exe and choose "run as an administrator". Then try to stop your service again and it should work fine.

NOTE: this is part of a new security feature built into Windows Vista and Windows 7