Adding a SharePoint server as a target fails with an authentication error on Microsoft Office SharePoint Server servers that only allow Client Certificate Authentication. If you use a configuration setting to skip verification of Sharepoint servers at the time of adding them or the server is already added as a target and later the Client Certificate Authentication is enforced then archiving fails with a "0x80004005" error in the dtrace.
"SharePoint target cannot be found" error appears on secondnd screen of the add a SharePoint target wizard when you enter the target URL and you find "0x80004005" errors in dtrace. If you check the IIS log you can find requests from EV server to EVCustom.aspx web service on the SharePoint server with a result of "403 7".
Enterprise Vault does not currently support Client Certificate Authentication so it doesn't work with servers that only allow this type of authentication.
This issue has been addressed as part of the following patch:
Enterprise Vault 9.0.3 - Release Details
Enterprise Vault 10.0.1 - Release Details
Any version of Enterprise Vault targeting a SharePoint Server 2003, 2007 or 2010 where Client Certificate Authentication is the only authentication method allowed.