Apple Mobile Device service will not start!

itunes 7.5
When I connect my iphone I get an error in iTunes saying: "This iPhone cannot be used because the Apple Mobile Device service is not started." When I run services.mcs and try to start the service I get a prompt saying "The Apple Mobile Device service on Local Computer started and stopped." I have tryed removing Apple Mobile Device service and reinstalling iTunes and I get the same results. Someone please help, what good is an iPhone that I can't sync.