Something that has been eluding a fix for me for the past several months was a strange bug when you inserted a teensy device into a VMWare Fusion based virtual machine. The way the teensy works is it emulates keyboard strokes and sends them to the victim machine. In my case, most of the keys stopped working, for example the start menu, uppercase characters, and others. What is strange about this one is that others using the exact same version of OSX with VMWare Fusion did not experience this problem. Symptoms: When you go to insert the teensy device, when it goes to hit the start menu it hits the recycle bin instead. Fix: Delete this file: /Users//Library/Preferences/loginwindow.plist, log out, log back in. This has seemed to remediate all my issues on the Teensy problem. Not sure if anyone else has been experiencing Teensy / VMWare Fusion issues but this one has been a frustrating one.