Yes I seem to have this type of problem
A new Teensy3.1 worked Ok downloading and running examples to the teensy only, nothing else connected and powered from USB
Then it just stopped and didnt download properly and then Windows Device manager kept detecting it and then dropping it.
The LED still flashes on it but randomly rather than repeated link in the blink sketch.
When I now compile Blink, it compiles and opens the loader, Arduino verbose tells me to press reset to download.
I press the button on the teensy board but looks like the Teensy Loader is not detecting it.....
When I switch on Teensy verbose in the Teensy loader it gives me the following...
14:29:22: Verbose Info event
14:29:26: Device came online, code_size = 262144
14:29:26: Board is: Teensy 3.1 (MK20DX256), version 1.03
14:29:26: File "Blink.cpp.hex". 14324 bytes, 5% used
14:29:26: HID/win32: HidD_GetPreparsedData ok, device still online
14:29:26: Device went offline
It tells me the device went offline although it is still plugged in
Is this a windows setup or drivers or hardware problem. Is there any other way of finding out what is happening....
Thanks