svchost.exe, store.exe and ntdll.dll

[Lukey]

Hello,
I am currently running Exchange 2003 SP1 on Server 2003. I have started getting the following error message. If anyone can shed any light on it, it would be much appreciated.
I don't know whether there is a problem with ntdll.dll opr something. This seemed to occur after applying some critical updates.

I am also receiving the same error but with store.exe instead of svchost.exe as the faulting application. This then stops all access to mailboxes

Thanks

Event Type: Error
Event Source: Application Error
Event Category: (100)
Event ID: 1000
Date: 12/08/2004
Time: 08:34:52
User: N/A
Computer: MSERVER
Description:
Faulting application svchost.exe, version 5.2.3790.0, faulting module ntdll.dll, version 5.2.3790.0, fault address 0x00007a6d.