I turned off my computer and when I turned it back my mousepad didn't work .When I log into computer using tab and enter , i get a black screen and a box that says "an unauthorized change was made to your license". My only options to choose from are validate online and close . I can't get on the internet to validate the computer which forces me to close . All programs I've downloaded within the last month have also been uninstalled as I didn't need them . Safe mode does work . Can anyone offer me a solution to my problem.