I have another head scratcher for you.  I have an oldish (5 years or so) HP laptop that I am running the current version of Kubuntu on.  Although I have had similar issues in the past, recently, my wireless connection has been acting up much more than usual.  Frequently, when I bring the laptop out of sleep mode, it will not detect all of the wireless networks around it.  For example, normally, there are 4 detectable wireless networks in my living room - two belong to me.  This morning, when I opened my laptop, it only detected my neighbors' networks - which are also the networks with the weakest signals.  My wife's laptop (running the current Kubuntu LTS version) does not have any problem finding and connecting to either of my wireless APs. 

Turning off and on the wireless connection does not solve the problem.  and iwlist produces some very unusual results: when running the command multiple times in succession, my APs showup and disappear from the results -  with the majority of executions of the command NOT showing my APs.