I have the same problem in 11.10, and it occured just before I installed 12.04, thought by remove and complete install 12.04 the problem wolud be gone , but no still there also in 12.04
i have a dell latitude with a intel 5100 wireless
it was working perfect before , dont know what happend or what i did .......... also the sudo commands where do you enter those , by alt f2 ?? or in the bios ??