Error 400: invalid request

I'm getting an error message in my email. I recently added a Webroot to my computer for security and after it ran scans and cleaned somethings up, my computer will no longer let me access my email. I keep getting the following error message: "You can't sign in to this app because it doesn't comply with Google's OAuth 2.0 policy for keeping apps secure." I don't know what to do. I tried removing my email hoping I could reload it in the mail app but it won't allow me to do that either. help! Thank you