What driver is in the device manager when you booted into recovery mode? Did you have the Android Composite ADB Interface driver like you do at regular startup. Or did you have the boot loader driver used. If you notice at least mine does change if you watch the Device Manager. This may be key for the rest of us, if there is a way to completely keep android Composite ADB Interface all the way through, as that works perfectly for me at least for doing adb shell at normal start up on the phone. Hope this helps.