"System extension cannot be used -- The system extension '//System/Library/Extensions/AppleUSBEthernetHost.kext' was installed properly and cannot be used..."

Hello.

Ever since I upgraded my Mac mini (mid-2011)'s Mac OS X 10.7.5 to 10.9.(4 and 5) so I could upgrade VMware Fusion Pro v6.0.4 to v7.0.0 to use 10.10 DP in guests, I kept seeing "System extension cannot be used -- The system extension '//System/Library/Extensions/AppleUSBEthernetHost.kext' was installed properly and cannot be used. Please try reinstalling it, or contact the provider's vendor for an update." http://i.imgur.com/UJ1Ge8o.png for a screen shot/capture from the guest VMs.

Does anyone know what's up with this? I see it in many Mac OS X guests (English and foreigns). I never had them before both software upgrades. Thank you in advance.