I have a massive problem with a new Macbook Air. It already came with Lion but I intended to install Snow Leopard, so performed a hard disk erase then proceeded to boot from a Mac Software USB drive but when holding down C it kept hanging at the Apple Logo Screen, no spinning wheel. Then I tried a SL DVD instead but instantly goes to a Kernal Panic (Unsupported CPU error) Command-R doesn't seem to work anymore and Internet Recovery also keeps failing. I've ran an Apple Hardware test and everything comes back as ok. I've resetted the PRAM/NVRAM and SMC which hasn't made any difference I'm completely out of ideas what to try next, I'm led to believe this could be the cause of a failed hard disk?