You are likely to repeat what allowed this to happen.
For now you can boot up some Live LINUX from USB and be safe. But until you understand what is going on, my answer is no.
You didn't tell enough to anyone to guess what happened.
I have a hacker on my computer if I go to another computer and logon would it be safe and not compromise that computer.

Chowhound
Comic Vine
GameFAQs
GameSpot
Giant Bomb
TechRepublic