exchange 2003 mailbox problem

I’m having a problem with Exchange 2003. This happened this happened this past Friday around 4 pm. The mailbox was unmounted. I tried to mount the mailboxes but there were errors. I notices that the Microsoft Exchange Information Store service was stopped.

Microsoft Exchange Information Store service will not start.
Could not start the Microsoft Exchange Information Store service on Local Computer
Error 1053: The service did not respond to the start or control request in a timely fashion.

Unable to mount mailbox.