Calendar reminders keep dinging

[craigeo]

Hoping someone can help me.
I have an X5 basic I've upgraded to 2003 A05.
Been running this way for a couple months fine.
Last 2 weeks it's started with a wierd issue.
It dings every 5 minutes for a calendar reminder.
But, the reminder doesn't show up on the screen so I can dismiss it. It's almost like it snoozes automatically. Then finally at what appears to be a random time the reminder shows up on the screen and I can dismiss it.
Anyone have any ideas?
Thanks in advance,
Craig