If you’re one of the many people who took the free upgrade option for Windows 10, you probably have the remains of a Windows 8 installation lurking about your hard drive, slowly getting in the way and causing all kinds of stupid things to happen. Windows 10 may be a slight improvement, but Microsoft has never been good at upgrades, and could have made life much easier if the installation just wiped the damn thing.
I highly recommend running the System File Checker after an upgrade, or if you’re having any stupid little problems with Windows 10. It’s fixing a fair few problems (notably error 0x800ccc13 in Outlook 2013), the command is:
Run this from an admin console, and let it work its magic, replacing any corrupted files it finds. With any luck, your Windows 10 machine will now run a little nicer, until of course you can do a clean install.