Nelson,
Trying to track this down, do you mean the .mpr or .mpx files had a later timestamp than the .mnx/.mnt files? Do you have Rebuild All and/or Recompile All checked on the project?
>No, the menu is not corrupted.
>It turned out what causing the problem is that one of the associated files has different datestamp. So when I updated the files (by opening and closing the menu), the problem went away.