Same "no more iPhone USB tethering" here.
- Mac OS X: 10.6.8
- iPhone: 4
- iOS: 5.1
- iTunes: 10.6.3
- iPhone Configuration Utility: 3.5
The cause is a faulty /System/Library/Extensions/AppleUSBEthernetHost.kext, though the version 2.3.0 is correct, its size of 78 KB, 60.892 bytes is not.
A known to be working AppleUSBEthernetHost.kext for iPhone USB tethering is version 2.3.0, but 225 KB, 189.646 bytes.
The fix is:
- In Terminal:
$ sudo rm -r /System/Library/Extensions/AppleUSBEthernetHost.kext# to remove - Restart (not sure whether this is necessary)
- Reinstall iTunes (in our case 10.6.3), this also installs the good AppleUSBEthernetHost.kext
When tethering still doesn't work:
- Apple menu > System Preferences > Networking > remove iPhone
- add the iPhone again
- hit the [Apply] button
PS According to our backup software somewhere around May 7th, 2010 a newer version of AppleUSBEthernetHost.kext was installed.