Maybe this?
viewtopic.php?f=30&t=7284
WI-Fi random disconnected from AP [SOLVED]
Re: WI-Fi random disconnected from AP
If it doesn't work, you might want to change to wicd. Even thought the changes initially appear to work over time NetworkManager proved to be unstable on my home network. I finally just gave up and switch to wicd.
“Don’t you see that the whole aim of Newspeak is to narrow the range of thought?"