If you have not already done so, start by doing a search on this forum for the "Divide By Zero" problem and you will find links and references to the fixes for your old FP2.6 which will resolve running on faster PC's.
Once your FP2.6 is patched, then verify if your problem persists.
Good Luck,
JRB-Bldr
VisionQuest Consulting
Business Analyst & CIO Consulting Services
CIOServices@yahoo.com