The drop down boxes in outlook no longer allow me to use the curser to select
a time or date when adding or ammending an appointment.  When I move the
curser away from the down arrow to select a time or date in the drop down box
the drop down disappears.  With the drop down box showing to select a start
or finish time I can still change the appointment time by using the mouse
scroll wheel.  The dropdown calendar box doesn't work at all.  I have to
manually type in a new date into the date box.  

The problem occurred in Office 2003 running on Windows XP Professional.  
Since then I have run the Office repair tool from the program, the repair
tool from the program disk and upgraded to Office Enterprise 2007 - all to no
avail in fixing the problem.  The only other change made to my computer
recently was the installation of a full version of System Mechanic 7 but I
don't know whether the problem started before or after this installation.