When I plug the usb cable from the Teensy into my computer, the LED comes on for a short period of time and then shuts off completely, indicating that the board isn't receiving power from the computer after it is first plugged in.

I checked the voltage between the GND and 3.3V pins and it is around 1.5V. The board powers on just fine and runs the blink program as expected when powered off an external supply, just not when connected to the usb port on my computer.

I have adjusted my settings to make sure the computer doesn't cut power to the usb ports. I have tried numerous cables and they all produce the same result.

Any suggestions as to how to fix this issue? Thanks!