Startup Defender is a small program that sits in your Windows tray and constantly monitors the startup locations on your PC to help prevent programs from auto starting up behind your back. If a program tries to write itself into any startup location Startup Defender will popup a windows and ask if the program is aloud to place itself to start automatically with Windows. Also you can disable/enable any programs that are currently installed to startup auotmatically. If there is an entry you are not sure what it is then you can Google it to see if it is needed or even harmful and choose if you want it to load it at startup or not. For the annoying programs that try to repeatedly place themselves in the autorun for Windows you can click the auto block so that Startup Defender stops them with out you having to bother with them any more.