We are seeing the following on an Ex2007 box on a Windows 2012 R2 DC domain:

Log Name: Application
Source: MSExchangeSA
Date: 07/12/2018 04:02:34
Event ID: 9408
Task Category: OAL Generator
Level: Error
Keywords: Classic
User: N/A
Computer: %ComputerName%.domain.suffix
Description:
OALGen failed to load the offline address book version 4 manifest file '\\%ComputerName%\ExchangeOAB\791205af-0a47-4e40-8238-8027a2062474\oab.xml'. This indicates data tampering or disk problems. Restore files in this folder from the recent backup or clean up folder content and force a full OAB generation.
Event Xml:



9408
2
13
0x80000000000000

896367
Application
%ComputerName%.domain.suffix



\\%ComputerName%\ExchangeOAB\791205af-0a47-4e40-8238-8027a2062474\oab.xml

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