Hey allen.c.h,
Thanks for the question. I understand you are experiencing issues with Personal Hotspot (via USB). The following resource may help to resolve your issue:
iOS: Troubleshooting Personal Hotspot
http://support.apple.com/kb/TS2756
USB troubleshooting
If you are using USB to connect your computer to Personal Hotspot and you are unable to get an Internet connection, check your computer's network settings. You may need to adjust your computer's network settings to disconnect and reconnect the USB Ethernet interface.
Mac OS X
Open System Preferences > Network. Locate and select the Ethernet adapter listed, and then click the gear icon and choose Make Service Inactive. Then choose Make Service Active:


Thanks,
Matt M.