There must have been SOMETHING that happened right before your games started to fail. I know that there are not a whole lot of games out there for Win2K (may be different in NZ), but if they were working fine and then all stopped all of a sudden... think back; did you install something or make another change to your PC?
When in doubt, reboot!
~ Laziness is the Mother of Technology ~
No animals or trees were harmed in the production of this post - however, several billion electrons were seriously inconvenienced.