Options Dialog Box Missing???

I was working in a book, and went to turn off auto-calculations, but the options dialog box will not appear. When I click Tools -> Options, nothing appears. Any other item on the tools drop down that has a dialog box is functioning properly. For example, when I click Tools->Customize, the customize dialog box appears....

I have tried opening other excel files, creating new excel books, and re-booting my machine, but still cannot get the box to appear...

HELP!!