Hey guys, I'm new here. Have just bought my first imac 24", its 2006 model I think, but I'm having trouble with it. So, I'm having the question mark folder error, and I'm trying to install a new OSX on to it, not fussed about any files being kept or anything else, just straight up clean install. Because I have dont have the disc, i have download a 10.7.2 dmg and burned it to a DVD, and have no success (it starts to load but goes to a grey screen with the mouse) and I cant boot from usb for some reason. Is there anything else I can try? I don't have another mac so everything is done on a windows machine, and have a windows keyboard so unsure of the apple keyboard buttons.