Before I upgraded to Panther, I did some spring cleaning of my hard drive, and inadvertantly duplicated a large disk image, completely filling my hard drive. After a boot into single-user mode to delete the huge files, I rebooted and found that my iChat prefs were apparently deleted. Ignoring it, I proceeded to install Panther, using an Upgrade Install. Since then, my AirPort network has not worked properly. Initially I suspected both the AirPort card and Base Station at fault, as I always had iChat opened, and never suspected it. The symptoms included losing DHCP addresses within minutes, and causing the base station to be unresponsive to soft resets; only cycling the power had any effect at all. I eventually got around to doing an archive and install, but to no effect. Recently, however, iChat crashed, and I didn't notice until my network was still running perfectly several hours later. So I deleted the iChat preferences, using [code] defaults delete com.apple.ichat [/code] to remove it. Oddly enough, that had no effect. Once I opened iChat, the network borked again. So I got out my Panther install discs, and used Pacifist to extract iChat, installing it over the version in 10.3.2. Still no effect. Then I tried closing iChat, deleting the prefs, and reinstalling iChat via Pacifist before trying again.
That was the key to fixing it (so far, I've not yet been on the network more than four hours at a time, but that's two hours more than the longest the network would work previously), at least for me. Apparently, the preferences had been merely corrupted, rather than deleted, and had subsequently corrupted the program, then the reverse happened after deleting just the preferences. YMMV, of course.
Mac OS X Hints
http://hints.macworld.com/article.php?story=20040109214356168