HL2.exe has a habit of not closing after you exit the mod meaning you get an error that the app is already running when you try to reload, this is nothing to do with the mod, but with Source SDK not being updated to function in a modern environment, only Valve can fix this issue... However, you can do the following...
Create a new text file on your desktop and add the following line...
taskkill /F /IM hl2.exe
Now rename it to "KillHL2.bat"... Or whatever name you wish to call it, as long as it has the .bat extension.
Now double click this to close Goldeneye Source (hl2.exe). Saves you going into processes.
Also, you could do what I have done and place this somewhere else, I have this bat file in my Goldeneye Source folder, you can create a shortcut for the desktop, then go to properties for the shortcut and change icon to Half Life 2 icon, saves you having that ugly batch icon on your desktop.
