I finally got an answer from Symantec. Enterprise Vault is not fully compatible with x64 based OS.
This is the email sent from Symantec;
My name is Steve from Symantec support. I've been assigned to case 411-XXX-7XX. In response to your question, at present Windows XP Professional 64 bit is not currently supported by Enterprise Vault. According to the latest compatibility guide: http://support.veritas.com/docs/276547 (pg 37) Windows XP Professional 64bit SP2 is currently in the (P)ending status.
This certainly does not mean that it will not work for you, it just means that Symantec's engineering has not made a final determination as to whether it would work 100% properly.
Please let me know if you have any further questions or concerns or if this case can be closed.