I think this error may be related to TBB SiteEdit 2009. They are trying to set the Blueprint context so that the parent component can be edited on the SiteEdit page without clicking the "Allow editing of parent objects" button
The current user may not have the rights to verify Blueprint, so this requires SiteEdit to need an administrator account.
This account is specified in the SiteEdit.config file (% TRIDION_HOME% \ SiteEdit 2009 \ SiteEdit \ Application \ Configuration \ SiteEdit.config)
the node you are looking for by default is as follows:
<AdministrativeUserId>Administrator</AdministrativeUserId>
This should be reset for the actual admin user, including the domain.
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