My Big Disk will not mount or is not detected. The System Profiler on my Mac or Device Manager on Windows lists it as unknown with the name TUSB6250 Boot Device.

Please try the following:

Disconnect all cables connected to the drive.
Connect the power cable to the drive.
Connect the USB-cable. First to the drive. Then to the computer.

If the drive is detected correctly the problem was probably caused by improper shutdown or un-mount (unplugging the cable without dismounting first, etc.). When this has happened, the USB-interface needs to reset itself properly. After this, reconnection should be no problem.