If any one else runs into this problem. The problem is related to computers that are retired and blacklisted.
1. To check the affected resources (Blacklisted + Disposed or Retired or Returned to Lessor) it's quite enough to execute the following prepared by me SQL query:
select * from inv_aex_ac_identification where _resourceguid IN (select _resourceguid from vasset where _ResourceGuid IN (select guid from AgentBlacklist) and (Status='Retired' or Status='Disposed' or Status='Returned to Lessor'))
2. Returned resources should be removed from the Resource Manager resource by resource... In my case there was only 3 resources, so it wasn't big deal to remove these :-)
3. Execute the Clean Up task
After you will apply the Solution and execute the Clean Up task again, feel free to check if the Software Inventory data class such like Add/ Remove or others has been successfully cleaned for Retired... resources with the query below:
"
select * from inv_aex_ac_identification
where _resourceguid IN (select distinct _resourceguid from dbo.Inv_AddRemoveProgram
where _ResourceGuid IN (select _ResourceGuid from vasset where Status='Retired'))
"
Thanks to Aleksandr Tampere in Symantec who helped me solve this problem in a fast an professional way.
Torb