Exchange 2k service wont start!

on my win 2k server Microsoft Exchange Information Store wont start i get the dependency error when i checked the dependecies i saw that they all start except (Microsoft Exchange System Attendant) when i try to start it i get this error:
“Could notstart…. on local computer. the service did not return an error. THis could be an internal Windows erroe or an internal service errie. If the problem persist, contact system admin”

please help
thank you