I know there are several topics on this subject but I couldn't find one that matched my isue My Spec: Macbook, 2.4ghz (?) Intel Procsesor, 4GB Ram, superdrive, 250GB Hard Disk (purchased off of eBay about 10 months ago) I was using my Mac to rip some DVD's to put on my iPhone (home made from files on my old PC one) using Islysoft DVD Ripper. Anyway, one of the files that it was ripping must have been bad as it was stuck for ages. It was also making a funy noise, later I found out that it was due to a poor label, it took quite a few attempts to get it out, ending up with the laptop being on its side so I could grab the DVD out of the superdrive. In the midst of all this I was trying to shut down the system as it had locked up, in theend I had to push the power button for10 seconds to get it to go off. Once I had got the DVD out I tried rebooting but it came up with a prohibitory/no entry sign and wouldn't let me in. I also had boot camp but the Windows partition was corrupt and had mising files too. I didn't get the original install disk with the machine, just a copy. When I tried installing this it must have been a bad burn as some of the files could not be loaded. So I went back to my Windows partition on BootCamp, re installed it and al was fine and dandy, it worked OK. So today I went out and got Snow Leopard from our local apple reseller (Square) and tried installing it. It came up with an error upon trying to install it, saying that it could not install on the original hard drive. After reading up on the net, it turned out I had to re partition. I decided that as I had not done much on Windows, I would go the whole hog and start off with a fresh 1 partition hard drive, as I use VMware fusion for my Windows use anyway. So, fresh new hard drive, now it allowed me to install. But I got a message saying installation failed, please contact the software vendor. I tried installing again and got the same message So seen as the hard drive has not worked for OSX since the crash, I am leaning towards that as being the problem. But I have also seen on here that it could be RAM also, possibly came unseated during earlier trying to get the DVD out? I am seriously considering getting a new hard drive as I am thinking of using my external hard drive for time machine as opposed to documents. But before I do I wanted to ask on here to make sure of what the problem is, before I spend out my money. It seems strange that Windows worked fine (albeit on a different partition) and OSX does not, but there you go, I ditched Vista to get away from all this palaver!