Error 80010108. Successful conection lost after 30 minutes.|Classic OPC: DA, A&E, HDA, XML-DA, etc.|Forum|OPC Foundation

Hello everybody,
I am trying to access to ExaOPC server of Yokogawa in a remote machine with an OPC client own developed in vb6. I get successful connection but about 30 minutes after, my client OPC launch 80010108 error. I have tried with Quick client of Kepware and its behaviour is the same. I have read in Google it is a problem with Windows 2000 Server and 2003 Server, but ExapOPC server is running in Windows server 2008 R2. By the other hand, I launch OsiSoft OPC client and it run without problem. I started three OPC client in the same time (my OPC client, OPC Quick client and OsiSoft OPC client) and after 30 minutes running successfully, my OPC client and OPC Quick client launch 80010108 error but OsiSoft client doesn´t fail.
Please, someone could help me?
Thanks,