Hey, I've been known to use win98 too, for games... The corp I work for uses mostly Dell and IBM equip- knowing what you have for equip would help, such as are they all one brand or not, and so on. We had a bad run of Dell kbd's that would lock up due to a bad firmware upgrade on one of their production runs. We found that it was only one set of serial numbers that were effected, and replaced the cooresponding numbers, which still took days.
BTW, we called it the sleeply keyboard syndrome, since it would just go to sleep, unless you removed the PS2 connector, and reseated it (not recommended) or restarted via the mouse. Either way, sounds very familiar...