Your network settings have been changed by another application FIX, PATCH, STOP, CORRECT

1. Open system preferences

2. DO NOT CLICK "Network"

3. Click once on "Sharing"

3. Click once on "Internet"

4. NOW, WITHOUT CLOSING THE FILE SHARING WINDOW Click "Show All" at the top of the file sharing window

5. Click once on "Network"

6. Bye, Bye, Pop-up

Easy solution works for me every time on OS 10.4.11