Exchange 5.5 errors in event viewer….

I’ve got a server running Nt4.0 server and exchange 5.5 Out of nowhere, nobody could access their inbox. When i looked at the server, an error was on the screen talking about a driver or service failing to load. The event viewer had 3 errors in it along the lines of 1). Database in inconsistent state initilizing the Ms.Exch.server information store database, 2). unable to initilize the Ms Exch. information store service,and 3). Unable to get the appletalk network address of the Ms. Exch. servercomputer.
The server is running service pack6 and exchange has service pack4 installed. Any suggestions would be much appreciated.
-Matt