Check the power management settings on your PC. It may not see streaming as "activity" and so shuts down the disc after a period. There may even be an option to allow streaming, depending on OS.
I've set up my Samsung BD C6500 (brand new) and installed Samsung PC Share Manager 2.5 on the server and all is connected through wireless network with excellent signal at the TV. Problem is that when I'm watching a streamed film, the Samsung loses connection with the router, sometimes after 5 minutes, sometimes after 15 minutes there is no consistency to it - except that it consistently loses connection!
So I've reconfigured the Samsung up for a wired network and run an ethernet cable from the router into the Samsung thinking that this would definitely sort out any gremlins in the wireless set up, but no, it's just as volatile and quits after a few minutes!!!
Please, someone tell me I didn't buy the wrong product did I?