Hi. I have Leopard 10.5.4 installed on my PB G4 When I try to update the OS it will download a 600+mb update then say the computer needs restarting. I let it restart then it displays a progress bar on top of the default Leopard desktop image. The bar will go up about 1/4 inch but never any further. I have tried it a couple of times but it's always the same. If I switch it off and back on again it restart in 10.5.4 normally. Any suggestions? I have 2GB ram and about 130GB free on the hard drive.