Hmm.. do what I would do. IF AV fails.. check your StartUP. by typing in msconfig in the RUN function. see if theres something unusual in there. and if that fails. re-check your CD Drive's IDS cable. which means you have to open ur box, dont be scared, i drink a can of coke while building and testing and repairing computers at work. it takes lots of carelessness to short out your computer LOL. just ermm.. stay away from the BACK of the motherboard. touch it and u go zzzzzzttt!!!. tho you always have the option to unplug ur PC while ur uncasing it LOL.