Ok guys, I had to visit to make sure you weren't lying. Lol virus, this is what made me have to shut down the computer and had to get ubuntu and then reinstall windows.
If you ever encounter this where firefox goes to like super small screen and then there's a popup saying crap like DO YOU WANT AN ANTIVIRUS.
As long as you don't press no or yes or escape on that window you're good.
To get out of it, goto Task Manager(Ctrl+Alt+Delete)..processes..and then find the process for your web browser.
iexplore.exe = internet explorer
firefox.exe = firefox
opera.exe = opera
(idk if this is right) safari.exe = Safari.
And then select it, and press delete key and then enter. Now idk for the others but when you exit out of firefox by ending the firefox.exe, when you start it back up again it will give you the option to start new session or where you goto where you were.
Start a new session and be win.