Hello Jason,
thank you for your reply.
The point ist that the system with the problem has even higher SAP_BASIS support package (SP-Level 0005) than the system without problem (SP-Level 0004). So the upgrade has not helped.
The system without problem is an IDES test system EHP7 for SAP ERP 6.0, Component: SAP_BASIS, Release: 740, Support Package Level: 0004, Highest Imported Support Package: SAPKB74004.
Do you know any good BC-forum? I couldn't find any BC-forum on SCN 
With best regards,
Robert