After the Exchange Migration Wizard Profile Update (EMWProf) updates a profile and migrates mailbox rules to the target server, the target Exchange Information Store may crash while attempting to update some of the rules.
Some rules may be correct in the source mailbox but appear to be corrupted in the target environment. The Information Store may crash if a rule on one of the mailboxes in the Information Store has been corrupted.
To resolve this Issue contact Microsoft Support for assistance. Please refer to the following Microsoft Support Knowledge Base articles for additional information:
Article #831276 for Exchange 2000:
You cannot access your mailbox and event ID 7031 is logged in the application event log in Exchange 2000 Server - http://support.microsoft.com/kb/831276/en-us
Article #833817 for Exchange 2003:
Store.exe quits unexpectedly and you cannot access any mailbox on an Exchange Server 2003 computer - http://support.microsoft.com/kb/833817/en-us