I just got this problem this morning. No icons on desktop, but I could start programs like taskmgr (which showed in task bar but did not display on desktop). So Machine was essentially unusable. Could (without seeing the dialog ) tab to shutdown of system, but that is about it.
Even the start options were modified so I could not start in safe mode.
Fortunately I had installed a new hard drive just 6 days ago, using an image copy of my system. I restored from this and am back in action.
This is the worst virus I have faced. Much worse than Others I have managed to remove from my machine or from friends machines. Makes case for Backup Backup Backup. I had found Macrium Reflect on the Internet and it worked flawlessly, my image backup to a $50 USB drive. Well worth it considering what would have happened had I not had it.
Good Luck.