The Windows Management Instrumentation service might not be running.
Start >> Run
Type services.msc
Press <Enter>
Scroll down to Windows Management Instrumentation and double-click on it.
Set Startup Type to "Automatic"
Click the "Start" button to start that service.
Click 'OK' to save the changes.
Now your "System" window should show correct information.
The WMI service should start automatically every time Windows starts in future.