"I believe the warning was related to accumulated detritus within the AppleUSBEthernetHost.kext"
Well, that's an interesting theory. Because the pop-up is sorta ambiguous. There is "installed improperly" and "cannot be used".
The latter certainly applies if there's a 64-bit only kext on a 32-bit only system! You could also claim installing a kext that is for the wrong architecture is also "installed improperly"
The question is though, if the kext isn't loaded, what does it impact? There must be something that uses that thing!
Isn't it just a driver for the Apple USB Ethernet adapter? Why would iTunes even include such a thing?
(I use one of those on a production Mac mini at work with Mac OS X Server 10.8.4 ... hmmn. Strangely, I updated to iTunes 11.4 on it, got the pop-up error, removed the .kext, reinstalled from the .dmg - AppleUSBEthernetHost.kext loaded and the driver/interface still works. Weird!)
... and, lo and behold, look:
[20:08] nightowl:/<1>Library/Extensions % pwd
/System/Library/Extensions
[20:13] nightowl:/<1>Library/Extensions % sudo kextload -v AppleUSBEthernetHost.kext
Requesting load of /System/Library/Extensions/AppleUSBEthernetHost.kext.
/System/Library/Extensions/AppleUSBEthernetHost.kext failed to load - (libkern/kext) link error; check the system/kernel logs for errors or try kextutil(8).
[20:20] nightowl:/<1>Library/Extensions % sudo kextutil -v AppleUSBEthernetHost.kext
/System/Library/Extensions/AppleUSBEthernetHost.kext appears to be loadable (not including linkage for on-disk libraries).
Loading /System/Library/Extensions/AppleUSBEthernetHost.kext.
(kernel) kxld[com.apple.macos.driver.AppleUSBEthernetHost]: The Mach-O file is malformed: Invalid segment type in MH_KEXT_BUNDLE kext: 42.
(kernel) Can't load kext com.apple.macos.driver.AppleUSBEthernetHost - link failed.
(kernel) Failed to load executable for kext com.apple.macos.driver.AppleUSBEthernetHost.
(kernel) Kext com.apple.macos.driver.AppleUSBEthernetHost failed to load (0xdc008016).
(kernel) Failed to load kext com.apple.macos.driver.AppleUSBEthernetHost (error 0xdc008016).
Failed to load /System/Library/Extensions/AppleUSBEthernetHost.kext - (libkern/kext) link error.
Failed to load /System/Library/Extensions/AppleUSBEthernetHost.kext - (libkern/kext) link error.
Check library declarations for your kext with kextlibs(8).
I can't even load it on my 64-bit Mac Pro!
A quick Google search finds
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https://developer.apple.com/library/mac/releasenotes/DeveloperTools/RN-Xcode/xc4 _release_notes/xc4_release_notes.html
Xcode 4.6.2 Release Notes
Changes
Building: Kernel Extensions
- Kernel extensions (kexts) built with Xcode 4.6.1 and 4.6.2 fail to load on OS X 10.6 and 10.7, and this error message appears in the console:
| kernel: kxld: The Mach-O file is malformed: Invalid segment type in MH_KEXT_BUNDLE kext: 42 |
To build kexts that load on OS X 10.6 and 10.7, on the targets that build the kexts, set the OS X Deployment Target build setting to OS X 10.6. 13645170
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So who knows what the Héll they built this thing on ...