Excel 2003 - Sheet Protection Causes Enter Key to Stop Working

[General Specific]

I have a sheet which works perfectly in Excel 2007. It is an xls.

When I protect the sheet, users who have Excel 2003 lose the use of
the ENTER key to advance to the next cell.

Help!

 

[ozgrid.com]

Unlock those cells they can change.

 

[General Specific]

Unlock those cells they can change.

Those cells are unlocked.

The sheet works perfectly in Excel 2007. On one of the Excel 2003
machines, we lose enter key functionality when we protect the sheet.