Outlook 2002

[booth]

I have a group of users that are having problems modifing
or deleting Calendar messages. The error messages that
we are recieving are:

"Copuld not save item. Your changes could not be saved
because you don't have permission to modify some or all
of the items in this folder."

"Can't open this item. The object could not be found."

Please provide recommendations!

Thanks,

Ed