I can confirm this exact same behavior on my Dell Inspiron 6000 (also w/ ipw2200 hardware). NM can't create or connect to ad-hoc networks (the association "ball" never goes green, so it doesn't even get to the DHCP step). Associating and acquiring an address using command line tools (iwconfig and dhclient) works fine.
-- ad-hoc networks don't work with ipw2200 https://launchpad.net/bugs/75358 -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs