Just mash F8 as soon as you power on until you get the startup menu.
Once in safe mode, press window+R to get the 'run' prompt, and run mrt.
I've been using various versions of Windows for a decade and a half with no AV software, and never encounter this stuff. I don't know if it's just because I don't trust anything that pops up, or if it's how my security settings are configured in my browser, but I seem to be teflon to this crap.
