Tonight, I put the computer to sleep and went out for a walk. When I returned, I pressed a key, which one I couldn't say....

Sorry, I didn't get back to you. I finally took the G5 to a shop with a good reputation, where I was told that it was a serious problem. The repairman ran all sorts of tests, before giving me the bad news. I forget what part died but I was told that it was one of the very expensive ones. The Repairman suggested that I could buy a used one and replace the bad part of that computer into mine. Or I could buy a new one with a warranty. I had some money at the time and bought an iMac. The Hard drives were in good shape and were rescued, enclosed and added to the iMac.