Blatant cut-n-paste from Ultimarc's site:
...This means that if you are connected using USB, this program will only work on boards shipped after August 1 2002.
For boards shipped before this date, USB mode will not work. If you are connected via the PS/2 keyboard interface, boards shipped before Aug 1 2002 MAY work but there are some complex I-PAC and PC issues which may prevent operation. This software is fully supported with either connection method and all Windows versions for boards shipped after Aug 1 2002.
You didn't mention how long you had your IPAC, but it sounds as if you have had it for quite a while, the new software may not work with it. Could that be the problem?