Event ID : 9175

Issue : The information store Service is not running.

Event Source: MSExchangeSA

Cause:
This issue can occur if the information store is not running. When the information store is stopped and the System Attendant is still running, the System Attendant keeps the MAPI session active. This issue can also occur if a mailbox store failed to mount.

Description :
We have observed an event which indicates that the Exchange Store is currently dismounted. Outlook client tries to query Information Store and store does not respond because it is down OR information store service is not started.

Action Required :
This issue can occur if the information store is not running. When the information store is stopped and the System Attendant is still running, the System Attendant keeps the MAPI session active. This issue can also occur if a mailbox store failed to mount.
To resolve this issue, verify that the information store is running. If the store is not running, attempt to start it. If the information store is running, and the event is still logged, verify that the mailbox stores are mounted. If they are not mounted, attempt to mount them.

Ref. Link: http://support.microsoft.com/kb/262456/en-us