[Nate the great]

Third times a charm:

C:\Program Files\calibre>calibre-debug -c "import wmi; from calibre.devices.kind
le.driver import KINDLE; k = KINDLE(); print [(str(drive.PNPDeviceID), k.windows
_get_drive_prefix(drive)) for drive in wmi.WMI().Win32_DiskDrive()]; k.open_wind
ows(); print k._main_prefix"
[('IDE\\DISKST3120213AS____________________________ _3.AHH___\\5&9C402E8&0&0.0.0'
, u'C:\\'), ('USBSTOR\\DISK&VEN_GENERIC&PROD_USB_CF_READER&REV _1.01\\2004888&1',
None), ('USBSTOR\\DISK&VEN_GENERIC&PROD_USB_MS_READER&REV _1.03\\2004888&3', Non
e), ('USBSTOR\\DISK&VEN_GENERIC&PROD_USB_SD_READER&REV _1.00\\2004888&0', None),
('USBSTOR\\DISK&VEN_GENERIC&PROD_USB_SM_READER&REV _1.02\\2004888&2', None), ('US
BSTOR\\DISK&VEN_KINDLE&PROD_CARD_STORAGE&REV_0399\ \B001BAB074470391&1', None), (
'USBSTOR\\DISK&VEN_KINDLE&PROD_INTERNAL_STORAGE&RE V_0399\\B001BAB074470391&0', u
'K:\\')]
Traceback (most recent call last):
File "debug.py", line 130, in <module>
File "debug.py", line 109, in main
File "<string>", line 1, in <module>
File "calibre\devices\usbms\device.pyo", line 191, in open_windows
calibre.devices.errors.DeviceError: Unable to detect the KINDLE disk drive. Try
rebooting.

C:\Program Files\calibre>pause
Press any key to continue . . .

And yes, the Kindle is connected.