Whenever I load up a multiplayer game, it spawns my character, then the green goes black and it says loading. It won't ever load, and I have deleted ALL of my save games for my GTA 4 game and it still does it.

Go to your GTA IV root folder (C:\Program Files (x86)\Rockstar Games\Grand Theft Auto IV) and then the LCPDFR folder inside it. Run the Diagnostic tool and in the ASI loader section, check if it says 'using xlive' if yes, delete the xlive.dll from your root folder and put in the dsound.dll from the LCPDFR manual install folder.

I am using dsound

Try removing some scripts or cars, go back to stock until it works, sometimes my game will act up like this if I have too many mods