Ooop! what is just happening? :o)
The usb or firewire often has infamous issues from time to time, either from OS or hardware. The LED is sometime on and sometime off that could be hardware issue (the small circuit board) and that sometime leads to deeper issue such as drive is not recognized or suddent RAW format!!!
Anyway, it is good to hear the problem is gone but I would not trust such device anymore. Also, make sure your system has enough power supply because usb could be failed if under power happens.
You might also request to refund the points if you have solved the problem yourself.
Happy New Year!