Enterprise Vault - Attachments cannot be opened

Hi, 

When the user tries to open up the attchments in his Vault, it comes up with the attached error. 

I tried to reinstall the Vault add-in and then reset the regitsry keys after deleting the existing vault cache and when his vault was synched, I find that the mails do not contain any attachments whatsoever. Infact most of the mails which display an attachment does not have any actual attachments in the mails. Previously the same mails used to carry attachments but when we tried to ppen up the attachments, the issue occured. 

This is crazy as I have no idea how those attachments dissapered and also - how the error comes up for those rare mails which are showing attached word or excel files in the archived messages under the vault.