Many older PC's are not up to running Windows 10. As your Toshiba is 5 years old, I imagine that could be your problem. Go to Toshiba's web site to see if your particular system is up to running the OS: http://us.toshiba.com/windows-10/upgrade If not, others on this board may be able to help you revert to Windows 7. I abandoned Microsoft 3 years ago and now use an Apple MacBook, so it would be difficult for me to walk you through reverting to your old OS,