I should add that doing a SELECT COUNT(*) [etc] querystring against the Excel files also returns the correct row count only on the local machine and not the server.  I've tried removing the lines on and around where the imports stop, but they still end on the exact same row number even when the data there is different.  I've saved out copies of the Excel sheets with columns removed and tried to load those.  They also work on the local machine, but fail on the server - but at different line numbers than the standard-width sheet.  The more columns I remove, the bigger OleDB thinks the result set is.  I tried adding a few dummy text columns instead, and, sure enough, the row count before failure shrunk.