using Excel 2003 protected sheets with older versions of Excel
 

I created a spreadsheet in Excel 2003 in which select cells are protected.
Some people are having trouble with the spreadsheet, and are getting the
'cell is protected' message on cells that I did not protect. I believe this
may be because they are using an older version of Excel. Is that possible?
I'm thinking I could perhaps save it as a different version but I'm not sure
if I can then use the same type of protection
Thanks for any help