I have starting getting this error after installing the latest iTunes update v11.4, loads of people all over the net are having this same issue. The system extension /System/Library/Extensions/AppleUSBEthernetHost.kext was installed improperly and cannot be used. Please try reinstalling it, or contact the products vendor for an update. I can just OK the box and carry on, but I would like to stop it, or fix it. Anybody know what this is and how I can fix this, or just wait for Apple ?