I just got a Manhattan True-Touch SuperPen graphic tablet. According to the instructions, I set it up right (all there was to do was plug in the USB port) and installed the software. My computer registers that it's installed, and the green light on it is on. The instructions say the light should be on for a bit and then shut off, but mine is flickering rapidly, and I can't make it register the pen or the wireless mouse. Help? Thanks in advance...