Exchange server 2003 offline defragment error

hi,
I am try to full backup of my exchange server using ntbackup but this task is not done , so i try to offline defrag of my database but it give me the following error, I am sure my all hardware is working fine.
and I think there was some issue in one my email account and i want to move this mailbox to another database, but i don't know which part of database having some issue, but my exchange server is working fine, only offline defragment and full backup issue which is not good for me , kindly help me to resolve this issue
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Event Type:      Error
Event Source:      ESE
Event Category:      Database Page Cache
Event ID:      474
Date:            7/19/2008
Time:            8:40:09 PM
User:            N/A
Computer:      EXCHANGE
Description:
eseutil (200) The database page read from the file "D:\exchange_data\priv1.edb" at offset 48991252480 (0x0000000b681b3000) (database page 11960754 (0xB681B2)) for 4096 (0x00001000) bytes failed verification due to a page checksum mismatch.  The expected checksum was 6539830557012247709 (0x5ac2253df9f5c49d) and the actual checksum was 2378286525918861837 (0x21015efe9f7dda0d).  The read operation will fail with error -1018 (0xfffffc06).  If this condition persists then please restore the database from a previous backup.  This problem is likely due to faulty hardware. Please contact your hardware vendor for further assistance diagnosing the problem.

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Regards,
Naresh