Check %APPDATA%\Microsoft\Windows\Start Menu\Programs\Startup\ for files and check %PROGRAMDATA%\Microsoft\Windows\Start Menu\Programs\Startup\. This is where user and system startup shortcuts are put, mainly user created ones, but not always.
Check %APPDATA%\Microsoft\Windows\Start Menu\Programs\Startup\ for files and check %PROGRAMDATA%\Microsoft\Windows\Start Menu\Programs\Startup\. This is where user and system startup shortcuts are put, mainly user created ones, but not always.