Exception from HRESULT: 0x80080005 (CO_E_SERVER_EXEC_FAILURE)) when i try to connect client .net app with OPC server

i have two .net apps:

1. the first allows to start OPC server
2. the second connects to the first to get data from the server.

The OPC server is saved in the register, but when i try to connect to the OPC server, an exception HRESULT is handled: Exception from HRESULT: 0x80080005 (CO_E_SERVER_EXEC_FAILURE)) Any suggestions about this exception please? Thanks alot