When ticking in Ethernet on Enable Port tab of Sony Notebook Setup, the mouse pointer change into a arrow pointer and PC hangs up.
Wait for a while until PC gets active. It takes a while to activate Ethernet port. Make sure that the mouse pointer changed back to normal arrow [Normal Select] rather than the pointer with hour glass [Working In Background], and wait for at least 30 seconds before goto Sony Notebook Setup to enable the Ethernet port.
It takes less time to enable Ethernet in Sony Notebook Setup than in Device Manager of System Properties.
1) Go into Sony Notebook Setup and choose Enable Port tab. Check in "Ethernet" and press OK button.
2) Leave it for a while and the dialogue box saying the following message pops up.
"You must restart the notebook before the new settings take effect. Do you want to restart now?"
3) Press "Yes" and PC automatically restarts to enable Ethernet.