After spending much time with a friendly but unable-to-help Dell technician I seem to have figured out the problem with my wife’s laptop myself (or at least found a way around it). It seems that for some reason her wireless driver crashes the whole system when trying to handle WPA encryption but it can handle WEP encryption fine. So we’re using that now. Not too elegant, but if it works don’t mess with it as I said earlier!
29 August 2006