After a recent automatic update to windows 10. the CPU on my computer went crazy. Explorer.exe or Windows Explorer in the Task Manager showed 35%+ CPU usage whilst doing nothing.
To fix this:
1. Look on your desktop for any icons that are not displaying (they might be blank or just displaying a strange icon)
2. Delete these icons or move them to a different directory
3. Restart your machine
Hope this works for you - it did for me. More information can be found at this Microsoft Answers link
