"My Calendar" problems

We are running Outlook 2003 Ver. 11.5608.5606 in our office. One of the
employees is having a terrible time with her "My Calendar" feature. When she
starts up Outlook in the morning, the calendars she has in "My Calendar" have
often disappeared, and are replaced with either (1) nothing, (2) "pocket
mirror" calendars which are blank, or (3) "Calendar in Mailbox."

If she opens her folder list & clicks on the calendar she wants to put back
in her My Calendar, it often only gives the option to "Remove from my
Calendar" and when she goes back it has magically reappeared. If it gives
her the "add to my calendar" option, often when she chooses that she will get
the blank "pocket mirror" calendar.

She is the only one having this problem and it will recur on its own
throughout the day -- after she gets all her calendars back in her "My
Calendar," at some point during the morning they will be gone and the other
oddities are back, even though she has not exited Outlook at any time.

Any ideas or suggestions short of heaving the machine out the window? I'm
starting to think a new install may be our only hope...

Thanks!