We have a real weird one here.

Server running Exchange 2000 SP3 and kept up to date, with mixture of
Outlook 2000 and 2003 clients.

Setting up meeting works ok, but if there is a change to a recurring
meeting, for example change of time, the meeting request returns "The e-mail
account does not exist at the organization this message was sent to. Check
the e-mail address, or contact the recipient directly to find out the correct
address."

The original meeting remains in the attendess diary, plus the revised time
meeting.
Is this because the revised meeting is still 'tentative' and waiting for a
reply (which won't come..)?

The original meeting attendee hasn't changed mail addresses, but we have
changed their mailstore locations after a server hardware failure.

Any ideas if it's possible that the mailstore location change is causing this?

I'm reluctant to redo all the meetings if it's not going to cure the problem.

Any help appreciated..