I have had this happen on both of my 2 iMacs, and was wondering what is the problem and if there is a fix. I bought an iMac 20" G5 Rev B this summer for my son to take to college, and after registering and booting up, it popped up a window that said "Keyboard Unrecognized" or similar with a "Next" button. On the next screen is a sideways picture of a keyboard and a request to press the key just to the right of the left shift key (Z on a US keyboard). When I pressed the key, it gave a message that I had pressed a key on the "build-in" keyboard (actual spelling) and it asked me to press a key on the "external" keyboard. We somehow got past this on the 20" iMac (I don't remember if we just closed the window or what) and it never came back. I just bought a second 17" refurb iMac (also Rev B) and it is now giving the same error. This happened on both 10.4 (as shipped) and after upgrading to 10.4.3 via Software Update. I tried closing the window, but it gives the same error every time that I start up the machine. What is this telling me? How do I get out of this?