Having downloaded Windows 10, whenever my computer is inactive the screen becomes black and will not respond. I've tried the enter key and on/off buttons which would normally work and ctrl-alt-delete doesn't work either. So far all I can do in press and hold the on/off button for 7 seconds to manually shut it down and then start it up again. Obviously when I do this I lose everything I've been working on which is becoming a bit of a nightmare. Additionally it seems to be shutting off my security software - neither of these problems were happening with the previous version of Windows. Please help!