I placed my hard drive from my hp pavilion into my new cooler master case and put my brothers z77 extreme 4 mobo in the case as well. I started my computer and windows 7 freezes and flashes blue screen then takes me to startup repair. Figured out the startup repair and it's now asking me "Reboot and Select proper Boot device or Insert Boot Media in selected Boot Device and press a key". Confused after reading other threads about OEM's and reactivating windows. Do I need a new OEM key or just buy a new windows 7 home premium disk? Help! Update: I believe my original computer came with windows already installed.