I have an '09 flashed to 5,1, running 10.7.5, which has been working fine since I got it about a year ago. I have been using a cheap MS usb mouse and the keyboard from a G4. As I said, this setup has worked fine until a few months ago, when I started to experience the intermittent loss of the keyboard and/or mouse. Usually, if I connect one or both of the devices to a different usb port things will start working again but sometimes I have actually needed to do a hard shutdown. An IT guy told me it could be the old keyboard or the on-board usb starting to fail. Rather than blindly starting to replace devices, is there some way I can test the usb? If, as I suspect, a diagnostic software like TechTool Pro will not be likely to help, I guess I need to try replacing keyboard/mouse or adding a usb card. I could switch to a bluetooth keyboard but would I not then lose the ability to connect a usb mouse or Wacom tablet to the keyboard? To stay with usb, seems my first move would be to replace the usb keyboard with a new one, then add usb card if needed. Would greatly appreciate suggestions as to where to begin.