Sounds more like a damaged view to me. Try starting Outlook once with the
/cleanviews command line switch. This switch (and a few other really helpful
ones) are discussed here:
http://support.microsoft.com/support/kb/articles/q156/9/82.asp

Signature
Russ Valentine
[MVP-Outlook]
> The majority of my Category/Contacts have disappeared from
> View By Category or the drop down box. The information
> still seems to be in place in Find/Advanced Search. How
> can I restore these Categories/Contacts into the View By
> Category system? Any help would be appreciated.