Running backup or Antivirus scanning against MS Exchange 2000 M drive may corrupt or remove server files. This will cause problems like Calendring issues, missing appoinments, Clients Cannot Access Attachments and emails etc.

Microsfot recommends not to scan 'Exchsrvr' and 'System32\Inetsrv ' folders.

Missing attachments can be accessed through POP3, IMAP4, and Outlook Web Access.