I have seen several references to this problem in the archives.  The
problem occurs where a contact has been assigned to more than one
category.  Typically, in the category window on the contact's
individual page, each category will be separated by a comma and a
space.  When the problem occurs, there is only the comma separting
categories, no space.  The effect of this is that when one does a view
of one's contacts by category, you don't get all of one category in a
single list.  For example you might get a list for Accountants, another
for Accountants,Manufacturing, another for Accountants,Service Industry
and so on.  If you are looking up Accountants, you have to go to many
individual lists to see them all.

I think Judy Gleeson MVP came closest to the cause on a Sept/06 post
when she said, "I have narrowed the problem down to Blackberry's.  This
issue only appears on PC's where Outlook is synced with a blackberry.
During the sync a flag is thrown about categories. All the users didn't
pay attention to it and just accepted it. Apparently the blackberry
doesn't know how to handle categories and during a sync operation it
strips the spaces away from the categories and leaves the categories
separated by only a comma. This in turn updates Outlook and leaves it
in a "broken" state. I am going to follow up with Blackberry."

I do use a blackberry so this makes sense to me.  My question to Judy
is, what happened and do we have a resolution?