I don't think it's a Windows problem, thus a repair install won't help. It seems obvious that some part of your system won't wake, for a reason or another. Try to leave it for, say, 20 minutes after start to warm up, and then log in? If restart works well, it indicates that the components work well once they are warm, but something doesn't work when cold. And that something could be anything, except software - it'll be hardware.
I repeat: if your computer has warranty, use it. It's a rather new product, isn't it?