How do you lock a client to a particular AP?

[mrcool at stupidgamerz.com]

Is there a way to lock a client on a particular access point?  I have found:
"iwconfig wlanX ap xx:xx:xx:xx:xx:xx"  which i presume is supposed to do
this... but didnt seem to have much effect.  On host_roaming, what are the
options?  (if any of this is in the README, then im blind).

Here is the situation.  After working beautifully for 2 weeks, my feed
mysteriously quits, so i check.  It has the correct essid/key and shows
signal strength, but the bssid is the wrong AP.  Change the essid to
something arbitrary (essid that), iwconfig wlan0 then returns an essid of
'default' (correct wep, and signal strength) and the incorrect bssid again.
(the same wrong one)  A couple of times, an iwconfig BACK to the correct
essid would make it reassociate correctly and start to work correctly again
(for a random amount of time).  But last time required a reboot to return it
to correct operation (make it associate to the correct AP).  

This is hostap in client mode.  Driver 0.2.4, 2.4.21 kernel.  The firmware on
the card is 1.3.6, but it IS in client mode.  I will ram flash it to 1.7.4 to
see if that helps, and re-install the driver, if perhaps it might have gotten
corrupted...  If anyone has any suggestions or ideas send them my way.  

Good luck

Jerryf