I recently caved in and upgraded my computer from Windows 7 to 10. I always expect a weeks worth of problem solving after any upgrade like this and Windows 10 has been no exception. In this case it lost all my files and settings any time I had to restart the system. Some were in the This PC/C:/Users folder, but not all of them. It also erased any new files saved to the Documents folder.
All my files were backed up. I learned that lesson the hard way a long time ago. So far my workaround has been to use the files on the backup, external hard drive. It’s seriously a pain to have to dig around to find the files every time I need them (some I use daily).
I noticed that my Wacom tablet was not functioning correctly either, which I figured was a driver conflict. The first step Wacom recommends is to uninstall all previous drivers. As soon as I did that, Windows 10 started working just fine. No lost files, no lost settings and no lost Start menu button. It even held up after installing the current Wacom drivers.
If you are having this issue with Windows 10, check your drivers. It could be a simple fix like this one was.