Possible Duplicate:
Internet Sharing is grey out
My Mac is connected to internet using WiFi and its working fine. I want to share the internet connection via LAN but I am unable to select the port (Ethernet) to be used for sharing in the internet sharing menu. Please see the screenshot attached.

Any solution to this problem?
@MacLemon: I almost never used Ethernet Interface (i am assuming that by removing/readding the interface you mean plugging/unplugging the ethernet wire).
– Jatin Kumar Nov 24 '12 at 06:19