Solution : https://service.sap.com/sap/support/notes/622130 (SAP Service marketplace login required)
Key words : 
existing http link occupies resource, status-dependent web applications, http connection setupwas exceeded, bw web applications reason, sap web application server, active bw web application, bw web application starts, 'rdisp/plugin_auto_logout' customizing parameter, 0b            import support package 13, 1c            import support package 07
Related Notes : 
       
| 625162 | Session handling in stateful BW Web applications | 
| 624511 | Known problems with stateless BW Web applications | 
| 619884 | Integration of BSP applications in BW Web Applications | 
| 589272 | Template attribute for automatic session management | 
| 539829 | SAPBWNews BW 3.1 Content Support Package 07 | 
| 523278 | SAPBWNews BW 3.0B Support Package 13 |