HTH, I solved my case like this:
Windows 7 (64). Mspdebug had been running fine, but Energia just could never write to the board.
For a last attempt I unpacked another Launchpad box, which happened to be a v1.5 board -- and voila! :-o
(BTW: is it the *FET* driver appearing in Device Manager as a Generic HID Device?)
Needless to say, it's mspdebug now that can no longer recognize the board...
I saw the libusb driver not appearing either, so I tried reinstalling it with its "inf-wizard".
And, hurray, mspdebug works again! Cool.
But... Umm... guess what... Energia is back again to "square 0"...: no unused FET found!
So... Either mspdebug (via libusb & "rf2500"), or Energia (via the FET driver?), this is the deal for me here.
But, at least, as it seems, I can get either of them running now, any time, for both v1.4 and v1.5 boards, just not at the same time.