so last night i changed from a gigabyte z77 board with win7 to an asus board, all hardware is working fine but when i go to boot i blue screen! i have a windows 7 upgrade pack that's been used on the same drive but i assume the code will not work when i type it in a second time!? question is how can i sort this out, i think i have to fresh install but with what i have can i do it? also, if i buy a win8 upgrade disc would that work? thanks and any and all tips help!