MS Office products randomly verifying/taking focus

Hi

Periodically, MS Office products throw up a dialog "Verifying Microsoft Word" (or excel or powerpoint or Outlook). The applications are not running and the notification comes to the front taking focus from whatever I am doing, which is driving me nuts. It does it for each of those apps within a few minutes. I wouldn't mind if it did it when I launch one of the apps or if it did it in the background but taking focus is NOT OK.

I have uninstalled and reinstalled the suite.

any insights gratefully received