Hi Alex,
Cognos Analytics can scan the Content Store for deleted users with no reference. Go to the Administration console and select "Configuration" -> "Content Administration". Click on the highlighted icon and select "Consistency Check..."

You'll create a new consistency check task. Give it a name and click "Next". Now you can select what kind of consistency you want to have checked. In your case it's the external one. You can select all namespaces or if you have more than just one, select the appropriate one.

Hit "Next" and select "Save and run once" and hit "Finish". The taks will look for broken references in you namespace.If you want to, you can also tell the task to fix the problems.

Hope this helps.
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Robert Dostal
Team Leader BI
GEMÜ
Ingelfingen
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