A couple days ago I started being redirected to a page that said welcome to nginx from google in both Firefox and Chrome. I ran a bunch of antivirus programs, including Malwarebyes and AVG, but they didn't come up with anything. So I uninstalled and reinstalled firefox and uninstalled google chrome completely and that seemed to solve the problem.
However, today when I turned on my computer and tried to open Firefox, my computer started running extremely slow and I couldn't open the task manager at all. I'm probably totally paranoid, but I'm worried that the virus has just been hanging around my computer somewhere. Is there a way that I detect it and then get rid of it?