This was posted by bigrushdog of EOS rom a while back.
The root of the problem is that adhoc is a depricated technology. That being said, the reason we are having issues is adhoc conflicts with wireless peer2peer, or p2p. This is a new wireless technology possible because ics has implemented the config80211 Linux wireless api stack. Some of you may have noticed a new wireless interface named p2p0 which is a member of the wlan0 control group. Also you may have noticed that p2p is also broke. I believe this is why some ics devices utilize two wpa_supplicant binaries. Also it looks like the kernel filters ibss beacons when the p2p0 interface is up. But Im pretty sure I found the source and its an easy fix. ICS is a very different Android from past releases. ICS is very forward looking and continues to merge with Linux common. Adhoc looks doable but I recommended adhoc fans upgrade their phones
xda-developers - View Single Post - [ROM][Nightly][ICS] Team Eos WiFi Nightlies (Wingray/MZ604)