Hi guys and thanks for looking. I only know about PCs so this is driving me up the wall. Cant tell you much about it other than its a mac g4 with IBM deskstar 30 gb HD.. [ making scratch scratch scratch - click - scratch --- sounds.. hope thats normal for now] matching usb keyboard & mouse.. all 4 ram slots full.. I have the OSX box / manual.. OSX and OS 9 discs. Im trying to reinstall the OS X.. if I dont start up with the cd I get the flashing question mark thing.. havnt left it for hours or anything to see if it moves on from that.. presuming it wont. Ok so I let it start normally [no C holding] with the CD.. I get to the install screen and proceed and it says it cant find OS 9.1 but I can upgrade after OSX gos on.. I continue but when it gets to choose the destination disc the hard drive isnt in it.. it only shows the grayed out CDROM... currently behind me Ive left it for 15 minutes so far..... no drive appears.. If I go into disc utility it picks up the disc, when I click verify it says in red 'invalid B-tree node' ..and somewhere else I forgot I read 'serious errors'.... also tried the same things via the OS9 disc. I go round in circles the repair dont work. I came across an 'initialise disc' question somewhere and said yes [chose extended, and standard in different attempts] and they fail straight away... tried erasing the disc from the top bar menu it seemed to be doing it but I dont know if it even has. It gives me the impression I need a better disc repair program? Or do I need a new hard disk or something? I have one but its not Mac.. does it matter? I wired it up instead of the other but it wont even find it in disk utility so I took it out. All your help would be appreciated.. it isnt my computer Im sorting it out for a friend. [late edit ] just adding that it was working fine before with what it has and the software there..