Thank you for posting such an elegant thread. This is the first post I have seen in a long time, where the user actually attempts to fix it himself/herself prior to asking around. And when I say you tried to fix it yourself, you even broke it down from the OSI perspective. Mad props man. Take a look at some of the posts from your peers (thread postings # wise) and you will see just what I mean. It actually angers me to read some of these posts.... Nuff said on that.
WICD is very tricky these days with BT5r2, a while back I made a thread about installing network-manager inconjunction with WICD and how to do it properly, so you could use them both (not at the same time ofc, but, if you did try, one would take the others settings, kinda neat...)... Try this out and let me know if it works for ya. Whenever WICD fidgets around with me, I pop open network manager and p00f, I get proper connectivity. If that is not the case, I would definately point my finger at yer broadcom NIC (broadcom sucks.... Hands down..)... Here it is.