I am sorry to hear you are having trouble with the Tic T500. Windows error code 0x1f indicates a general failure and it does not tell us much about what actually went wrong. It should be fine for the Tic T500 to be unpowered (or powered only from USB) for long periods of time.
What was connected to your Tic when this error happened? Was the Tic powered when it happened? Was your stepper motor energized, and was it moving? Could you send us some pictures of your setup so we can check your connections? Is the Tic connected directly to your computer, or is it connected via a USB hub?
The next time the error happens, please look at the LEDs on the Tic to see what each of them are doing. Also, please try closing and reopening the Tic software and see if that fixes the error. If that does not work, please try unplugging the Tic from USB and plugging it back in. Let us know the results.
We have seen cases before where errors like this are caused by electrical noise getting to the computer, causing its USB port to go into a bad state. If that is happening to you, you might try connecting the Tic to your computer using a USB cable with ferrite beads on both ends.