Unscannable file rule

Hello All,

Environment :Exchnage 2010 SP2

OS: wINDOWS 2008 R2 Enterprise with SP1

The below mentioned error message is observed when teh users send/receives the excel file.

The attachment  located in message with subject, located in inbox has violated the following policy settings:
    Scan: Auto-Protect
    Rule: Unscannable File Rule
The following actions were taken on it:
    The attachment  was Logged Only for the following reason(s):
Scan Engine Error.  The maximum file size within a container was exceeded. at location pivotCacheRecords2.xml within pivotCache

For more information, visit http://www.symantec.com/business/support/index?pag... .

The recommendations mentioned in the symantec article are already verified.