Here's my method, useful if you don't know which process is launching the scam:
I tried safe mode but the pc just loaded then rebooted (the virus detects safe mode and reboots)
Use safe mode with command prompt instead. When the command prompt opens type explorer.exe to open up a desktop (the virus wont load as it runs from your user profile), now you can go to control panel and create a new user with admin rights.
Reboot and login with your usual profile and wait for the virus to load it's thing, now press ctrl+alt+delete and choose switch user and load up the new user (no virus for this user).
Now ctrl+alt+delete and choose task manager then processes and click show processes from all users, organise the results so you can see all the processes from the user with the virus. End each process for that user.
Now ctrl+alt+del again and switch back to the virus user and you should get a blank screen if no desktop, this is ok just ctrl+alt+del again and start task manager again, click top left "file" and start new task and type explorer.
Now you should have a desktop in the original user but without the virus, open up your browser and google for malwarebytes, get it, let it update and do a quick scan, it will find and remove all the nasties, reboot and voila!!
seems like a lot of stuff but it's 10 minutes to setup.
Just a recap,
safe mode command prompt, start explorer, create a new user, reboot to original user let the virus load, switch to new user, task manager, kill processes from original user, switch back to original user, task manager start new explorer, grab malwarebytes and scan.