Hi,
The message is not an alarming one, kext is loaded even if the message appears.
Origin is located in :
[FONT=Verdana, Geneva, sans-serif]/System/Library/Extensions/AppleKextExcludeList.kext/Contents/Info.plist[/FONT]
[FONT=Verdana, Geneva, sans-serif]Which only allow 1.2.5 version of GenericUSBXHCI kext and multi beast one is newer.
For some reason (small issue causing USB3 drive not be recognized immediately after boot, need to enter sleep and wake up to work fine) i've got install the latest 1.2.7 version of the driver and i change value in this file before installing and did not got the message.[/FONT]