Hello Dave,
What version of windows are you running? winkey+r will open run dialog box, key in winver and hit enter. You will get a prompt showing your version of windows, let us know which version it is.
Might you possibly have any network related software installed? Neat write up HERE outlining a few steps you can take for running system file check and using DISMto verify integrity of your operating system data.
As always be sure to have a recent backup of all of your data before further troubleshooting.