Trouble after upgrading to exchange 2000

Hi

I get this error message after upgrading my exchange 5.5 sp4 to exchange 2000.
This is the errorcode I get in the sysmtemlog:
The Microsoft Exchange Information Store service terminated with service-specific error 0.
Event id 7024.

In application log I get this one:
Unable to initialize the Microsoft Exchange Information Store service. Error 0xc0040391.
The computer is a win2000 sp4 server.
Event id 5000

Any idea why?

Kind regards

//Hakan