No pull-down menu access in Excel workbook

When adding an Excel workbook to my Flexpro database I do get the excel pull-down menu in the top of the screen but when I click on any item in this menu I do not get the pop up part of the pull-down menu. I have reinstalled Flexpro 7 but this had no effect. All the Excel toolbar items do work. I currently use Excel 2003 SP2.
How can I solve this problem?