Symantec fails to backup by indicating there is a corruption

Hi.

I have an Exchange 2010 SP1 environment that appears to be ok, except when Backup Exec runs to backup the Databases it fails with the following:

Backup- \\{DAG NAME}\Microsoft Information Store\{DB NAME}

V-79-57344-65247 - A failure occurred reading an object.

Backup

Writer Name: Microsoft Exchange Replica Writer, Writer ID: {76FE1AC4-15F7-4BCD-987E-8E1ACB462FB7}, Last error: The VSS Writer failed, but the operation can be retried (0x800423f3), State: Stable (1).

Note: The Microsoft Exchange backup was made from the passive copy of the database on server MNZ-DUN-MBX1.

The consistency check of the snapshot for the Microsoft Exchange database Database was successful.

V-79-57344-65247 - A failure occurred reading an object.

WARNING: "\\{DAG NAME}\Microsoft Information Store\{DB NAME}\Database" is a corrupt file. This file cannot verify.

The consistency check of the snapshot for the Microsoft Exchange transaction log Logs ( E02002AB2D3.log - E02002B3748.log ) has failed. You should check for possible data corruption in the transaction log that is online.

The log files then do not get cleared down. These errors appear with all databases and I’ve tried a few things to try and clear it.

I tried forcing Backup Exec to use the active database VSS writer and the problem persists. I moved all databases to one server and have tried both nodes in the DAG and both fail. I tried with circular logging to clear up the log files. I've tried disabling AV scanning. I have moved all users from one Database and have tried eseutil on the effectively empty DB to run the /r switch to ensure it was in a clean shutdown state but this makes no difference.

Is there anything else I should be looking at to verify what the corruption is and ho to go about sorting it.