Mapi services

When I try to use any third party application on the pc it gives the following error message.
Mapi services are not available on this system
we are using windows 2000 pro service pack 2
outlook 2000 connected to an exchange 200 server.

It worked one day and then did not the next

Please email me if possiable at
jeffrey.frisbee@faypwc.com

Thanks!