@MOHPHR : I am facing the same issue as you.
I tried several ROMs from Original stock ICS to Paranoid to Crisleko's ROM.
Going into the airplane mode and then turning wifi on used to work, not anymore.
3G Data works just fine, not being able to use wifi is frustrating because when I leave it alone, it connects by itself randomly when I am at home for example.
I have done some extensive research and found an article that mentions wifi hardware problems resulting from ICS update on a galaxy S2. (Google: Samsung Galaxy S2 WiFi Issue BY Shaiful Borhan )
I did use the *#*#526#*#* and got the status: "NotSet Driver loaded [NG]".
Anyone can help please ?