I am running Windows 8.1. My T3.5 board works perfectly and I've never had a situation where the computer does not recognize the T3.5. I am running SamplePlayer sketch with an audio shield. It runs fine on my T3.5. I hooked up my new T4 and it worked for an hour or so and now I continually get the error "No Teensy boards were found on any USB ports of your computer. Please press the PROGRAM MODE BUTTON on your Teensy to upload your sketch."

Nothing works on the T4. I switched everything back to my T3.5 and everything works. What might be going on? I've rebooted my computer twice and that did not help. I've looked through the forums and PJRC website and followed troubleshooting advice, but nothing has fixed the problem. My computer won't detect my T4.