[mergen3107]

I had the same just a few days ago! However my Kindle was working at that time and I wanted just to wipe internal settings.
So what I did and how did I resolve:
1) On my laptop there are 2 USB ports, one of them turned out to be faulty. It can handle a USB mouse receiver easily, but some USB sticks and Kindle can't mount.
2) Since I use Kubrick from a stick, one port is always busy (and the stick must stay in the port in order Kubrick to work as it should).
3) So I used good port for Kubrick first, because Kubrick did not boot from bad port.
4) Booted from Kubrick, tried to get Kindle into this mode in bad port, no success.
5) Then in Windows I just tried plugging usb stick and Kindle to this bad port - they didn't mount as usually. However, after some playing with the port, Kubrick was able to boot from bad port and worked perfectly then, however Kinlde couldn't mount still.
6) So I used now good port for Kindle, and bad port for Kubrick. After that Kubrick was able to find Kindle straight a way!

So my suggestion for you is to try mounting some usb sticks with the port you were using for Kindle to see if you can start Kubrick from it, and use the port you used for Kubrick for Kindle. Or use a (powered) USB hub in your port that you used to mount Kubrick. Or boot to Kubrick from a CD/DVD and use the working USB for Kindle.

Good luck!