Solution : https://service.sap.com/sap/support/notes/1351213 (SAP Service marketplace login required)
Key words : 
attached source code corrections, symptom /sapapo/om_check_activities, find invalid times, displayed inconsistencies dumps, system displays inconsistencies, dummy activities, spp requests, solution implement
Related Notes : 
       
| 1292734 | /SAPAPO/OM_LC_UPGRADE_70: Problems during upgrade | 
| 1065366 | /SAPAPO/OM_LC_UPGRADE_51: Problems during the upgrade | 
| 932837 | /SAPAPO/OM_LC_UPGRADE_50: Problems during upgrade |