this morning most of my calendar data was gone

the computer was left on overnight. the data is still showing up in
recurring appointments, but seemingly without reason, only some of the
recurring appointments are showing. there are no filters. nothing i
do seems to get the recurring appointments to show up in the day's
calendar. most of them show up when i first open outlook and it gives
me a list of the day's appoinments. my reminders tell me that the
appointments are there, but i don't see them in the calendar. windows
xp. i can create new recurring appointments and they show up. we
copied my pst file and loaded it onto our laptop and some of the
recurring appointments show up there, a couple more than our main
computer, but still not all of them. we've randomly lost appointments
before, but this is bizarre. HELP?!

and i just found my security settings in my email were changed, it was
asking for a security certificate, which i had to figure out how to
disable.