I've tried holding c down and clicking the Install Mac OS X icon inside the mounted CD and it just stays with the spinning icon on the Apple flash screen and I end up having to force shut down. It boots into OS X fine. The discs in question are the original gray discs that come with the Mac Mini but I have had my memory upgraded from 512MB to 2GB a few days ago. Could this be the problem? I've tried resetting the PRAM too. My Mac Mini is a 2006 Intel Core Solo model. Any help appreciated, Thanks. Edit: Found out it was partition related that's causing the disc not to boot past the Apple splash screen. I accidentally deleted the hidden OEM partition when messing with partitions (and this is what makes the grey discs ability to boot into the installer). I went to an Apple authorised service provider near my area and they tested a retail copy of the Mac Box Set of Snow Leopard and it booted into it fine - purchased Snow Leopard Mac Box Set yesterday, installed perfectly . If you have Tiger or don't have leopard currently installed, you need to purchase the Mac Box Set of Snow Leopard at approximately £129/$169.