Solution : https://service.sap.com/sap/support/notes/481019 (SAP Service marketplace login required)
Key words :
folders <inqmyroot>/server/managers/log, log files exist reason, dos box disappears immediately, <inqmyroot>/dispatcher/managers/log, stable dos box, <inqmyroot>/dispatcher, program files, java_homeenvironment variable, windowsstart menu, start menu