Comms broken then fixed by recent Windows updates

Hi,

We develop software (which has worked fine for years from the days of DOS
3.3 till recently) to control our hardware devices via the serial ports.
(Most of our machines are now Win XP SP2 and now only come with USB ports but
USB to Serial adapters worked fine.) A recent (automatic - it's corporate
policy) update broke our communications with our hardware. RS232 and USB
comms were BOTH broken. The next update, however, fixed the problem. Our
customers climbed the wall during the down period. We would obviously like to
prevent this from re-occurring. Any ideas? Where can I find a list of driver
updates automatically installed by Windows update so we can at least tell our
customers what to uninstall?

Thanks in advance,

Ralph Bryce