you might try looking for an outlook fix tool. IIRC there was one built into office.
I am not sure why you chose a hard drive forum instead of a windows forum, as usually if you direct your query to the appropriate place you get better results.
you don't say what you have already tried, if anything, but google pulled up this:
Calendar Checking Tool for Outlook - Version 2.4
http://www.microsoft.com/en-au/download/details.aspx?id=28786