C# is no good with low level windows functionality. You need to use pInvoke, to call the necessary APIs. You would need to use FindWindow to find your specific window, as all objects in windows are windows themselves. Then use EnableWindow to disable that window. Use Spy++ to find out window names, or better yet, use CreateToolSnapshot to get PIDs.
As for services, Codeproject helps you:
http://www.codeproject.com/KB/system...ceManager.aspx
If you want to do it the API way, use OpenSCManager, OpenService, ControlService and CloseServiceHandle.
Again, I'm not familiar enough with C# to suggest, but as for API use RegisterHotKey to disable alt tab.
If you arent familiar with pinvoke, use
www.pinvoke.net for instant function definitions.