Teensy 3.1 with Windows 8 Help Needed

Hello,
When I run the last version of serial_install.exe I receive the message like the picture and my PC Under Windows 8.1 don't detect the teensy 3.1. I tryed to install the version 1.18 of teensyduino all run ok without error but the PC don't detect the teensy 3.1 again. what's false in my process ?
Thanks for your help

Oh, the stand-alone installer still has the old unsigned driver.

I'll update it soon.

Regarding detecting Teensy 3.1, please see the "No Serial Port While Programming" part of this page:

http://www.pjrc.com/teensy/troubleshoot.html

By default, Teensy is a USB HID device, not serial. It only becomes serial when you program it to be serial.

While in programming mode (having pressed the button so the LED stops blinking), look for it like this:

http://www.pjrc.com/teensy/check_halfkay_vista.html