Comment 28 for bug 92742

I've found by accident how to "fix" that - if security mode is 'restricted' and key is set, then running:
iwconfig ra0 key off
iwconfig ra0 key [1] (or something else - just setting key back)
switches card back to security mode 'open' and it associates with ap - link quality and everything else gets back to normal! Hope it works for others too.