Hi citojaso,
Welcome to the site!
I'm not 100% sure whats caused this for you, so lets go through a few things..
First a few questions I have for you..
Did you uninstall WinMX and Peerguardian (if you had PeerGuardian) and then reinstall the WinMXGroup patch version?
What Operating system are you using?
What does the update bar say on your WinMX? Patch Operational, Please Be Patient, or is it White blank bar under your version details and connection details located at the very top.
What firewalls are you using ?
If you could tell me that, it would help us to help you..