Folder with question mark at startup

It is clear that sometimes the computer is not able to see its operating system. Maybe this is due to a corruption problem or the drive may be failing. if you are using Bootcamp, I assume that a Mac OS is installed. That may be where the problem is. Try restarting while holding the Option key down to start up in the Mac OS. Then run its Disk Utility and see what it reports.

Boot into Safe Mode by booting with the Shift key held down and check there to see if the problem persists.  Reboot normally and test again.

NOTE: Safe Mode boot can take up to 10 minutes as it's doing the following; 

• Verifies your startup disk and attempts to repair directory issues, if needed

• Loads only required kernel extensions (prevents 3rd party kernel/extensions from loading)

• Prevents Startup Items and Login Items from opening automatically

• Disables user-installed fonts 

• Deletes font caches, kernel cache, and other system cache files