Download Malawarebytes - Free version from here …
Run it and let it do its stuff.
IF it cannot run, then get VKILL from that link I gave you above, and run that to prevent the malware from stopping malawarebytes.
Doug … I was nearly ‘caught’ by precisely the same System tools fake message …
I just straightway phoned my antivirus company, and they remote-accessed my computer and fixed it in the way I am recommenting to you.
this is also a method recommended and described by Geoff … you know … used to post as HaXX)r on the old forum.
OK …
Ah … and yes … AVOID toushing or clicking anywhere withihn that nasty window … even the X at the top. Either rebood computer when it happens, or Call up task manager and close your browser.