That's two of us it's driving nuts now! However, I've just been looking around on the internet and it does appear that in some circumstances other broadcom drivers can interfere with the ability of the broadcom-wl to work.
That's a pity as you have a broadcom wired ethernet device and if my suspicions turn out to be correct you may not ever get them both working without configuration changes each time you want to use the other.
We'll see IF there is an answer to that later.
For the moment you may care to edit the file:
you'll need to do that as root, and add the lines:
I think some of those are superfluous, but lets try a shotgun approach.
After that reboot the machine and see what wireless does.
If it doesn't make any difference, and you are relying on the wireless machine to post, you'll need to remove those lines and reboot again to get the wired interface to work.
I'll look for your reply with interest!