Amazon Kindle Keyboard (3rd Generation) 4GB, Wi-Fi, 6in - Graphite
I had this issue with the frozen screen, after many failed attempts at trying to reset etc.. I discharged the battery, and the Kindle itself, re-installed the battery, plugged it into my laptop, the amber light came on so I just left it, after 30 minutes I heard the USB noise from the laptop (the windows notification noise that a USB device has been plugged/unplugged) then the Kindle screen flashed black and white a couple of times then the loading screen with the tree showed up, after 5 minutes of waiting I was at the USB Drive Mode screen, now its all back to normal fully working. If you have this issue just be patient it takes a lil time as there is no instant fix that magically resets it straight away. From what ive seen its down to low battery, while reading a text intensive book (ie small text and a lot of it per page) this then drains the battery to the point that it becomes unresponsive but due to how the LCD screen works the last image will remain on the screen which makes it appear to look frozen when in fact its actually just Dead and needs charging.
Hope this helps you guys