Wilfred, I am going to venture one idea. I do this because I have an identical iBook and I have never seen this warning. I am guessing that the system software was reinstalled using the wrong setup disks. I assume that Powerbook discs were used. I would suggest that you look into that possibility. I would look into buying or somehow getting your hands on a retail version of OS-X. I also think that you can find the original system discs for your G3 iBook on eBay. Do you know what I mean? Do you know the difference between these two versions of discs? I use Tiger on my G3-600mhz. It works very well. However I do have 320mb of ram. Hope this helps, Bill Montreal