Can not delete appointment

I have a problem with outlook where as I can not delete an appointment. The
appointment had an attachment which I deleted but since then the appointment
still believes it has an attachment. The error message I am getting when I
try to delete it is "Could not open one or more attachments". If I try to
modify it I get another message; "The item cannot be saved to this folder.
The folder was deleted or you do not have permission. Do you want to save a
copy of it in the default folder for the item?". Also I cannot dismiss the
reminder only snooze it.

I am using Oulook 2007 with Exchange Server 2003.

Any help would be apprciated.

Thanks

Shane Cavanagh.