Eireless

I have a puzzle that has shown up in a couple of places but so far have not
found the solution, only a theory. I hope you can shed some light on this.
The problem arises when a working wireless installation of XP laptops with
NO encryption added has the recent set of MS Windows updates added. Suddenly
the wireless stops accessing the network.

Brands of hardware are not common on the sites so thats probably not the
issue.

WAPs are set with no encryption and no mac addressing filtering. Some of the
new service packs are showing SP2.

Rolling back the updates and all is well again.

Have you come across this? Have the over zealous security changes stopped
wireless without encryption from been used?

My guess is that one or more of the new downloads affects the wireless and
is blocking it.

Any ideas are appreciated.