I have a Compaq 615 laptop, currently running Win 7. Wanting to upgrade to Win 8 Pro, I successfully downloaded Win 8 which took about 5 hours. The installation seemed to go fine, but then I got the message "installation was unsuccessful, restoring your previous version". (Which it did). No explanation about the failed install. How do I get past this? Must I start the download all over again, or can I just redo the install process? I have already paid for the download and don't feel like paying again!