it happens to two type clients:
Lightstreamer Silverlight Client Library version 1.1.3537.25900
Lightstreamer Web Client Library version 4.3.1 build 1355.3

here is the sequence for one example:

Server log:
12:23:20,754 |INFO |LightstreamerLogger.requests |SERVER POOLED THREAD 2 |Starting new session: Sb84ee213e3d2eb08T2320753 from 10.35.185.113:40654
12:23:21,055 |INFO |LightstreamerLogger.requests |SERVER POOLED THREAD 8 |Serving request: /lightstream/control.txt?LS_session=Sb84ee213e3d2eb08T2320753&L S_op=add&LS_table=1&LS_id=ADAPTER&LS_mode=RAW&LS_s chema=MESSAGEID+DATA+MESSAGE_TS&LS_data_adapter=DA TA_ADAPTER from 10.35.185.113:40654
12:23:21,056 |INFO |LightstreamerLogger.requests |SERVER POOLED THREAD 8 |Controlling session: Sb84ee213e3d2eb08T2320753 from 10.35.185.113:40654
12:23:51,297 |INFO |LightstreamerLogger.requests |SERVER POOLED THREAD 2 |Polling (2) to session: Sb84ee213e3d2eb08T2320753 from 10.35.185.113:40652
.....
13:04:30,879 |INFO |LightstreamerLogger.requests |SERVER POOLED THREAD 1 |Polling (83) to session: Sb84ee213e3d2eb08T2320753 from 10.35.185.113:41139

In the metadata adapter log:
13:05:05,885 |INFO |Logger.METADATA |FOR PUMPS PARKING DESTROYER|User 139d2143-e865-4757-9d24-9e56b13071af has 0 concurrent session(s).

But after this all the bin_session.txt request still got 200 back but client stopped receiving data

Thanks