To solve the problem, this is what I've done:
- Start Task Manager (Windows Key+X, or right click on the time at bottom right corner), find "Skype". (Press "More details" if you cannot find the app)
- Right click on "Skype" and select "Properties"
- In the "Properties" of "Skype", go to the "Compatibility" tab.
- Check the box "Run this program in compatibility mode for", and select "Windows 7" from the list.
- Restart your Skype or restart your computer.