This is the error log. All other exchange services have started except the IS. Unable to mount or dismount store or start IS service. any ideas!!! ==================================================================================== A transient failure has occurred. The problem may resolve itself in awhile. The service will retry in 56 seconds. Diagnostic information: Cannot open mailbox /o=First Organization/ou=Exchange Administrative Group (FYDIBOHF23SPDLT)/cn=Configuration/cn=Servers/cn=SVR01/cn=Microsoft System Attendant. Microsoft.Exchange.Data.Storage.ConnectionFailedTransientException: Cannot open mailbox /o=First Organization/ou=Exchange Administrative Group (FYDIBOHF23SPDLT)/cn=Configuration/cn=Servers/cn=SVR01/cn=Microsoft System Attendant. ---> Microsoft.Mapi.MapiExceptionNetworkError: MapiExceptionNetworkError: Unable to make connection to the server. (hr=0x80040115, ec=-2147221227) Diagnostic context: ...... Lid: 12696 dwParam: 0x6D9 Msg: EEInfo: Generation Time: 2011-01-31 02:33:53:749 Lid: 10648 dwParam: 0x6D9 Msg: EEInfo: Generating component: 2 Lid: 14744 dwParam: 0x6D9 Msg: EEInfo: Status: 1753 Lid: 9624 dwParam: 0x6D9 Msg: EEInfo: Detection location: 501 Lid: 13720 dwParam: 0x6D9 Msg: EEInfo: Flags: 0 Lid: 11672 dwParam: 0x6D9 Msg: EEInfo: NumberOfParameters: 4 Lid: 8856 dwParam: 0x6D9 Msg: EEInfo: prm[0]: Unicode string: ncacn_ip_tcp Lid: 8856 dwParam: 0x6D9 Msg: EEInfo: prm[1]: Unicode string: SVR01.domain.local Lid: 12952 dwParam: 0x6D9 Msg: EEInfo: prm[2]: Long val: -1527653632 Lid: 12952 dwParam: 0x6D9 Msg: EEInfo: prm[3]: Long val: 382312662 Lid: 19778 Lid: 27970 StoreEc: 0x80040115 Lid: 17730 Lid: 25922 StoreEc: 0x80040115 at Microsoft.Mapi.MapiExceptionHelper.ThrowIfError(String message, Int32 hresult, Int32 ec, DiagnosticContext diagCtx) at Microsoft.Mapi.ExRpcConnection.Create(ConnectionCache connectionCache, ExRpcConnectionCreateFlag createFlags, ConnectFlag connectFlags, String serverDn, String userDn, String user, String domain, String password, String httpProxyServerName, Int32 ulConMod, Int32 lcidString, Int32 lcidSort, Int32 cpid, Int32 cReconnectIntervalInMins, Int32 cbRpcBufferSize, Int32 cbAuxBufferSize) at Microsoft.Mapi.ConnectionCache.OpenMapiStore(String mailboxDn, Guid mailboxGuid, Guid mdbGuid, ClientIdentityInfo clientIdentity, String userDnAs, OpenStoreFlag openStoreFlags, CultureInfo cultureInfo, String applicationId) at Microsoft.Mapi.ConnectionCache.OpenMailbox(String mailboxDn, Guid mailboxGuid, Guid mdbGuid, WindowsIdentity windowsIdentityAs, String userDnAs, OpenStoreFlag openStoreFlags, CultureInfo cultureInfo, String applicationId) at Microsoft.Exchange.Data.Storage.ConnectionCachePool.OpenMailbox(String serverDn, String userDn, String mailboxDn, Guid mailboxGuid, Guid mdbGuid, Object identity, ConnectFlag connectFlag, OpenStoreFlag openStoreFlag, CultureInfo cultureInfo, String clientInfoString, Boolean secondTry) --- End of inner exception stack trace --- at Microsoft.Exchange.Data.Storage.ConnectionCachePool.OpenMailbox(String serverDn, String userDn, String mailboxDn, Guid mailboxGuid, Guid mdbGuid, Object identity, ConnectFlag connectFlag, OpenStoreFlag openStoreFlag, CultureInfo cultureInfo, String clientInfoString, Boolean secondTry) at Microsoft.Exchange.Data.Storage.ConnectionCachePool.OpenMailbox(String serverDn, String userDn, String mailboxDn, Guid mailboxGuid, Guid mdbGuid, Object identity, ConnectFlag connectFlag, OpenStoreFlag openStoreFlag, CultureInfo cultureInfo, String clientInfoString, Boolean secondTry) at Microsoft.Exchange.Data.Storage.ConnectionCachePool.OpenMailbox(String serverDn, String userDn, String mailboxDn, Guid mailboxGuid, Guid mdbGuid, Object identity, ConnectFlag connectFlag, OpenStoreFlag openStoreFlag, CultureInfo cultureInfo, String clientInfoString) at Microsoft.Exchange.Data.Storage.MailboxSession.Initialize(LogonType logonType, ExchangePrincipal owner, DelegateLogonUser delegateUser, Object identity, OpenMailboxSessionFlags flags) at Microsoft.Exchange.Data.Storage.MailboxSession.CreateMailboxSession(LogonType logonType, ExchangePrincipal owner, DelegateLogonUser delegateUser, Object identity, OpenMailboxSessionFlags flags, CultureInfo cultureInfo, String clientInfoString) at Microsoft.Exchange.Data.Storage.MailboxSession.OpenAsAdmin(ExchangePrincipal mailboxOwner, CultureInfo cultureInfo, String clientInfoString, Boolean useLocalRpc, Boolean ignoreHomeMdb) at Microsoft.Exchange.Data.Storage.MailboxSession.OpenAsAdmin(ExchangePrincipal mailboxOwner, CultureInfo cultureInfo, String clientInfoString) at Microsoft.Exchange.Servicelets.SystemAttendantMailbox.Servicelet.Work()

Problem resolved...disabled Forefront security and hay presto IS can be mounted again!