Extortionware or fake security software

As soon as it shows up

Do Not Click Any thing
Press your computers power button and Hold it in until your computer shuts off
call me: or turn on your computer go into safe mode. run ccleaner. look in programs and features for the offending software and remove it if you are sure of what you are doing. Reboot into normal mode. Update your anti virus and scan. Update windows. Make sure your auto scan and defragmenter are set to scan very night. don't use Screen savers(I am not talking about wall papper) or sleep/Hibernate modes

Alternate is Press Alt + F4. Or Ctrl + Alt + Delete. Click End Task. then go to step 2