Yeah that is definitely a problem with the service EXE rather than the way you are trying to start it. It basically means that you have something in your service's "Start" method (or it might be called OnStart or something like that) that hangs or takes too long. That Start method needs to complete and return within a maximum of I think 30 seconds - most services start within a couple of seconds. So I would do some debugging within that method of your service and see where it is getting stuck on the Windows 7 machines.

Oh and by the way, you can start services via managed .NET code, you don't need to use Windows API for that Just use the System.ServiceProcess.ServiceController class (although I guess it might be easier to use that Windows API if you already have a handle to the service from creating it)