XL97 – Spin Button Control Tab Missing

I have to deal with a weird problem.

A user running OFF97 Pro SR2b with W2K SP2 is missing a tab in Excel 97.

When you insert “spin buttons” from the Forms toolbar, you can normally right-click them to access the Format options. Once in the Format window, there’s a tab called Control in which you can specify the min and max values as well as the linked cell, etc… Unfortunately, on that machine, the Control tab is missing ! She has the 3 first tabs, but no Control tab. Then she cannot set the spin buttons’ properties as she would like to.
I already searched a bit on TechNet but didn’t find anything relevant. I uninstalled and renstalled the whole Office package and re-applied the SR2. This occurs for any document. She has full admin rights on her machine.
Any idea plz?