Ms Exchange 2003

I am not able to get the system attendant to start, I have read lots of posts and still am unable to find a solution.

I receive this error when trying to view my server from the system manager:

Operation : retrieving mount information
ID no: C1040721
Exchange System Manager

Mailbox unvailable, Ms Exchange services not start, no problems with DNS, have read so many post / articles but still moving in cricles! help please!