|Did you delete the entries detected by Malwarebytes? Have you tried running a System Restore to a time before your "friend" visited?|
Just a suggestion; next time give your friend an account with limited privileges so he can't break your machine.
Are you running any anti-virus software? If not, you should.
"So won’t you give this man his wings
What a shame
To have to beg you to see
We’re not all the same
What a shame" - Shinedown