Solution : https://service.sap.com/sap/support/notes/784979 (SAP Service marketplace login required)
Key words : 
sapbwnews bw sp09 netweaver'04 stack 10, system deletes query entries, flat files cache modes, 10 content            import support package 19, 0b            import support package 25, 50            import support package 10, 1 content support package 19, delete program reason, rsr_cachethe program works, delete entries found
Related Notes : 
       
| 1643106 | Cache entries deleted by RSR_CACHE_RSRV_CHECK_ENTRIES | 
| 1497989 | Faults in report for deleting old cache entries | 
| 1107434 | OLAP cache consultation: Long wait times due to locks | 
| 791065 | OLAP cache with flat files -> cache is not used | 
| 763336 | SAPBWNews BW Support Package 10 NW '04 Stack 10 RIN | 
| 723261 | SAPBWNews BW 3.1 Content Support Package 19 | 
| 723254 | SAPBWNews BW 3.0B Support Package 25 |