That's weird. If only the speakers are disconnected, it should still show the sound card in the dxdiag. We'll see. If sound doesn't work once you have the speakers reconnected, let me know.
Okay, since the laptop recognizes it, the disc is okay, and there might be some incompatibility with your other computers dvd drive.
I can't be sure if it will help, but you can try
updating the dvd drive to the latest firmware, if you haven't done so yet.
If you want to do troubleshooting for your laptop, please post its dxdiag too.
Also please post the exact error message regarding the dll.
Your network issue sounds weird. How does it "say you are online"?