Ok, Have a iMac G5 with built in BT. I used it downstairs yesterday and took it back to the spare room where it usually is used. Fired it up today and I find that the BT mouse is fine BUT it ignores the keyboard. I tried; Replacing batteries. Checked that the suspect keyboard worked on my mac mini (it did). Tried my other BT keyboard on the iMac same problem. So, why does it recognise the mouse but not the keyboard? I do not have a USB Keyboard, so now I cannot Log in to fix it! I am guessing that the pairing has gone BUT surely it would simply see the keyboard as a new one and start setting it up. Something is stopping keyboards working with BT, very strange - could a loose BT module cause this? Or will I have to buy a USB Keyboard now to use my iMac?