I am using Outlook 2007 on Vista and cannot send out new appointments in the
calendar.  Despite having allocated a colour category, the message "category
must be entered" is displayed again and again at each attempt to "send".  I
am able to save and close the new appointment without sending it.  How do I
either switch categories off (we don't even use them) or get this to work
properly?  I would hate to revert to Office 2003 (I love Office 2007) but
this will force me to do so unless I can successfully create and send out new
appointments.  Please help!