If my memory is right I think the Irda software is loaded at startup. Go to start-run and type msconfig. Look in the the startup tab for a reference to either it or the software. If you find it, untick the box and reboot. Then do a search for any reference to it in start-search.
I think this is the way I upgraded a nokia 7650 from IrDa to a bluetooth dongle. Quite a while ago though.;)