Same problem here.
I'm using Netgear usb adaptor.
When I return to the PC it's gone to sleep
(even though I have tuned-off the hibernating/sleeping functions)
Space bar should bring it back within seconds.
Sometimes it does sometimes it doesn't.
Often I have lost my Internet connection and cannot get the pc to reconnect.
Shutting down just hangs.
To re-boot, I can only press the power button and count ten...