Memory Problem when screen is off

I have been using Win10 for the past 4 or 5 months and in general I have been pleased with its performance. However over the past couple of weeks I have noticed an issue when I switch off my screen and leave the machine idle. After about 5 mins I can hear the sound made when a USB is unplugged, and then immediately after the sound made when a USB device is plugged in. This continues intermittently for an hour or so.

If I return next day, when I switch the screen on the memory usage is sky high, usually I have lost my desktop and all icons but slowly the system recovers itself. My machine has been on an hour this morning but the memory usage is still running at 670mb or 77%.

Also I am sure this is related, when I reboot my machine I lose the position of my desktop icons.

How can I debug this issues, it's a shame because this is spoiling my experience of Win10 and I'm not so keen to tell everyone how great it is as I was during the first weeks of using Win10.

Thanks in advance.

I think I have identified the problem, I had recently installed a Bluetooth 4.0 USB dongle which Windows installed drivers for automatically. I tried the drivers on the provided manufacturers disk and since then the issue seems to have stopped.