We have that same issue whatever device we plug... USB HDD or pendrives.
Working on Windows 7: computer seems hanging, taskbar icon for removable devices displays there is "a device" but not its name, and windows explorer doesn't "see" the device.
It is not easy to diagnose. I haven't been able to get rules. But it is somewhat related to "Action when inserting external devices".
Device control is always disabled
- Worst behaviour: untick "Action when..." (which is my preferred option) (windows registry: "AskForScanOfRemovableDevice"=0) - Best behaviour: tick "Action when..." and select "Display scan options" (or whatever it be in English; "Mostrar opciones de análisis" in Spanish) (windows registry: "AskForScanOfRemovableDevice"=1) (windows registry: "AskForScanOfRemovableDeviceDefaultAction=2")
