Dude,
1,first of all i did a clean install of lion got the Ethernet to work with Muiltbeast 3.7
2,reboot
3, delete AppleHDA.kext from /System/Library/Extensions
4, reboot
5, run Kext Utility
6, Reboot
7 run Kext utility and drag AppleHDA.kext into it <----------
8 Reboot
9 run Muilt beast...