Alarms Won’t Clear in Groupwise 5.2.4

I have seen several instances when an alarm pops up before an appointment and the user clears it. One minute later, the alarm goes off again and again and again. We finally deleted the appointment and the alarm finally went away.

Another instance was that the user said that he had to clear the alarm several times before it would disappear.

I researched this and have not been able to find an explanation for this problem. Can anyone help?