emove 'A network cable is unplugged' icon from tray

Click on Start>Run..., type regedit.exe and click OK. Delete this key:
HKEY_CLASSES_ROOT\CLSID\{7007ACCF-3202-11D1-AAD2-00805FC1270E}
Restart to apply the changes. I haven't had any ill effects so far. Make a backup of the key just in case (select the key and click on File>Export...).


Source: http://tweaks.com