Solution : https://service.sap.com/sap/support/notes/660715 (SAP Service marketplace login required)
Key words : 
ace authorization check returns, user context cache comprises, im_super_type importing parameter, delete_ucc_of_sy_uname private methods, user context calculation, user context cache, attached correction instructions, cross-application server, user context, cache reason
Related Notes : 
       
| 1156745 | CRM 4.0 SP Stack 15 (07/2008) Release & Information Note | 
| 844193 | CRM 4.0 SP Stack 09 (07/2005) Release & Info. Note | 
| 797340 | CRM 4.0 SP Stack 1/2005 (SAPKU40008): Release & Info. Note | 
| 761607 | CRM 4.0 SP Stack 9/2004 (SAPKU40007): Release & Info. Note | 
| 754723 | CRM 4.0 SP Stack 9/2004 Support Release 1: Release Note | 
| 743291 | CRM 4.0 SP Stack 6/2004 (SAPKU40006): Release & Info. Note | 
| 696262 | CRM 4.0 SP Stack 1/2004 (SAPKU40004): Release & Info. Note | 
| 677456 | SAPKU40003: Support Package 03 for CRM 4.0 |