Get the key with an application called keyfinder. Uninstall windows on your current machine and install it to another, but make sure you call Microsoft that you've switched computer so they can manually activate your new PC.
Obviously your PC is out of date. It is time for an upgrade. Your processing speed is not fast enough for streaming videos. The best thing to do is just buy a new PC or upgrade to a better CPU.
Do you have any Drive Emulation softwares installed, such as, Daemon tools or something like that? I heard those virtual drives can screw with your physical drives.