Question : enterprise vault doesn't work on a pc

enterprise vault doesn't install on a pc but does not give an error
actuall it does install without error but the toolbar never shows up and the icons don't change in Outlook. Which doesn't aloow us then to stt archived attachments.

Answer : enterprise vault doesn't work on a pc

That will do it since the entry is already in the sql table but now you have a different SID.  Make sure that if you ever delete a user or disable in AD that you disable archiving in EV for it.