I has this on and off for months. Did all the solutions from online which worked for a time but it would randomly come back. Since I removed Avast it hasn't come back once. Although like the ex wife I'm sure it will show it ugly face round here again someday.....
Its very random and different people with different setup and programs seem to have suffered it at some point with different solutions. Mostly those who did upgrade from 8.1
I got it and I upgraded from 7.