I have worked with HSSF quite a bit and have many functionalities that work; 
however, I have run into a problem reading in the workbook when the file was 
created using Open Office on a Linux machine.  I couldn't find any issues that 
dealt with Excel files that weren't generated using Microsoft Office, but I 
have a good feeling you can't open a file that was created in Open Office.  I 
can tell you that I copied the information from the file created in Open 
Office, copy and pasted into an Excel sheet created in Microsoft Office and 
that worked fine.  Thanks for your help and/or comments.