Messaging Interface Error

[SystemDown]

One of my Outlook 2000 SR-1 users is experiencing a random error when sending e-mails w/attachments or when attaching files to e-mails. The error is "The messaging interface has returned an unknown error. If the problem persists, restart Outlook". I check on technet and installed the SP for Office but this error still occurrs. No event is generated in the event log.
Any ideas?

 

[joegz]

Are they all using the same e-mail editor type or does it vary? joegz
"Sometimes you just need to find out what it's not first to figure out what it is."

 

[SystemDown]

This specific error is only occurring on a single workstation but, our Exchange server is having preformance issues in dealing with attachments, randomly users will receive errors of "Outlook could not open one or more attachments". I was curious to know if this particular error was related to Exchange or Outlook.
To answer, no one is using MS Word as there Outlook editor.