Solution : https://service.sap.com/sap/support/notes/566719 (SAP Service marketplace login required)
Key words : 
terms business explorer analyzer, business explorer analyzer, bw server terminates, logon screen reappears, excel xp reason, 0b front-end, solution install patch 5, analyzer restarts, analyzer menu, bex browser
Related Notes : 
       
| 559043 | BW 3.0B Front-End Patch 05 | 
| 542961 | Business Explorer Analyzer loses BW connection |