Sounds like the laptop is turning off due to high temperatures. Make sure all vents are dust free and the intakes aren't being blocked when used. If the laptop is old the thermal paste might be wearing off causing less than optimal heat dissipation. You may have to bring it to someone who knows...
Hi there,
Can you open a command prompt (Windows key + R > Type cmd into run) and type ipconfig /all.
Then can you right click the window and select all. And then copy and paste it here for me.
Thanks,
I believe its you're sound card or lack of sound card. If your computer can't output 5.1 it's only going to output a stereo signal to the 2 main speakers.