Cannot delete meeting requests sent to distribution lists-Outlook

[Beach Lover]

A staff member created several different recurring meetings using Outlook
2003. She has since upgraded to Office 2007. She invited people using
individual e-mail addresses and also people in two different distribution
lists. When she attempts to cancel any of these meetings, the following
happens:

She opens the meeting and clicks CANCEL MEETING and then clicks SEND
CANCELLATION. She then gets the following error: "The item could not be
found." She clicks OK and then tries to expand the distribution list(s) and
get the following error: "The name or distribution list has been deleted and
is no longer a valid address book entry. The operation failed. An object
could not be found."

The distribution lists are in her CONTACTS and she can send meeting requests
to them. She just can't cancel or update meetings.

She is running Office 2007, SP1.

 

[Beach Lover]

Update....these are NOT recurring appointments. They are just individual
appointments.