I'm not hopeful I can get help here, but I'll give it a try.

I'm on XP, using Excel 2003.

I have a somewhat wide spreadsheet (up to column IT).

I read this spreadsheet with the Jakarta POI HSSF framework, written
specifically for reading Excel files.

When I run the app that uses POI, if I only read the leftmost columns,
it works fine. However, once I get up to about column 65 (somewhere
around BP), I get the following bizarre exception from POI:

org.apache.poi.hssf.record.RecordFormatException: Coding Error:
Expected ExpPtg to be converted from Shared to Non-Shared Formula

I've filed a POI bug for this, and asked around on the dev list, but
I've gotten nowhere.

I've tried experiments of creating multiple worksheets, each
containing blocks of about 50-60 columns from the original worksheet,
and that works, although it's somewhat laborious.

I'm hoping there may be an Excel expert who really knows about the
innards that might have a feel for what could be happening here, and
how I could deal with it, or how POI HSSF could be modified to deal
with it.