I have had a big issue since I started using Office Outlook 2007 at work,
with Outlook reminders that could not be closed, even though the meeting had
been deleted and removed from my Calendar.
I figured out that the problem is caused by calendar items that were deleted
from my exchange server still being stuck in my offline items folder on my PC.
To resolve this, I opened the Outlook calendar, then right clicked on the
calendar in the "My Calendar's" section on the left frame of the window, then
selected properties.
Once the Properties dialog box appeared, I selected the "Clear Offline
Items" button, which scared me at first because it removed all of my calendar
events, but the next time I started outlook, it pulled them all back down
from the exchange server, and the annoying reminders that would not go aware
were finally gone!
I hope it helps in the future. It's a lot quicker than other resolutions I
read.