dstumbler and wi0 errors

I've been having a problem that I've been testing for a week or two now.  I
have 2 different wireless cards that I've been using.  I have a Linksys
WPC11v3 and a D-Link DWL-650.  I'm running FreeBSD 4.6.2-RELEASE on a Dell
Latitude CPi laptop.

Both cards are recognized by FreeBSD by pccardd on insertion.  I can use
both cards to connect to an AP and do all the regular things I do on the
internet.  The problem that I have is when I wardrive with dstumbler.  I
seem to be able to walk in and out of various AP ranges without problems,
but when I drive in and out of one quickly, my screen will slowly fill up
with the following errors:

wi0: timeout in wi_cmd 0x0002; event status 0x8001
wi0: wi_cmd: busy bit won't clear
wi0: init failed

I'm not sure exactly when this happens, but it seems to be only when I'm in
my car, and I move in and out of an AP range quickly.  When this happens,
the entire system becomes unresponsive.  I can't Ctrl + C, or use the Ctrl +
Alt + Del keys to restart the machine, type any keys, switch virtual
terminals, etc.  It happens with both cards.  The fastest way to get the
system out of this state is to eject the wireless card.  Then after
reinsertion, the card will work fine again.

Since the wireless card works fine with everything except dstumbler, it
leads me to believe that dstumbler might be the problem, maybe with the way
it uses the wi driver?  So my question is, has anyone else come across
problems like this?  Has anyone found a solution?  Would a different version
of FreeBSD work better?  Would a different card work better?  Are there any
other stumbler programs out there for BSD or Linux that anyone have found to
work?

Any help is appreciated.
Thanks!
Aaron