Airport Express on but drops wlan connection


chemical precursor
I bought a refurb Airport Express from Apple about 6 months ago and finally got around to installing it & setting up printing and airtunes. For a while everything has been fine, but in the last couple of weeks, SOMETHING is going haywire.

While working and online with my PBG4 connecting to airport express, I lose my DHCP provided IP address and end up with a self assigned IP. The Airport status in the menubar says full strength, still connected to my WLAN. Airport Admin Utility doesnt show the unit when you scan for it. The Airport Setup assistant sees it & on keychain authorization, it errors ( i forget the exact error ).

Restarting the PB doesnt re-connect. Restarting the AirExpress doesnt fix it.
Sometimes it just magically fixes itself. Leave it alone long enough and in all probablility, it will work again. But today I got fed up.

Has anyone heard of this problem? Any suggestions?
my suggestion is to hard reset the ae and set it up again.
this cured various, similar, issues I had with my ae.
well, maybe... I thought I'd tried that ( level one reset ) but i dont know that it made any difference. the intermittent nature of the problem doesnt suggest configuration. it happened again tonight...

i will try super-reset again.