If all cells in a column have the property word wrap set, it is possible that the method org.apache.poi.ss.usermodel.Sheet.autoSizeColumn(int) returns a width that is much too narrow. This does not seem to appear all the time, and it is possible that the specific Excel version used to view the file, may recalculate the widths to make the sheet look nice. The hardware and OS are just guesses, and I will add hopefully better details.