Replicator Page crashed

After Updating from 5.0.11 to 6.0.3 (both German) several Notes Clients get the following problem:The replicator (page) doesn’t work (Startup botton as well as the schedulted replication)and the Client crashed. Any ideas ?

Moreover a complete new Client installation of ND 6.0.3 (with the original \data and notes.ini) get no problems !

Thanks in advance - Regards /TOM