The latest (2014-07-12) update of the free AVG AntiVirus protection for Windows gives a false positive for teensy.exe and offers to deal with this "threat".
Do not select the "Protect Me" option. Instead click on "More options" to allow teensy.exe to continue running as normal. AVG will note that this has been added to the list of exceptions.
Do not select the "Protect Me" option. Instead click on "More options" to allow teensy.exe to continue running as normal. AVG will note that this has been added to the list of exceptions.