Many users find that once they have set up their firewalls and routers to allow WinMX they still have difficulty getting uploads to work correctly. If your running Norton Antivirus 2005 or later you will need to allow WinMX in the Internet Worm Protection.
This is very easy and leaves you completely protected still. Just follow steps 1-9 below.
Thats it, once you have this done its not usually necessary to reboot your machine or WinMX for it to take effect. Your uploads should work just fine now.