windows 7 freezes

I installed Windows 7 using boot camp on my MacBook Air 2013. Windows randomly locks up when I am working, even if I am not working and it's just sitting there. I don't get a BSOD. The laptop just stops responding and I have to cycle power. The Windows logs only seem to show that windows shutdown unexpectedly. A couple months back I tried a clean install to see if that would help but it has not. I have all firmware and boot camp updates that I can find available. I don't have much software installed in Windows except Office 2013 and Chrome.

Thoughts? This is driving me nuts. I may have to try returning the laptop to Apple but it's probably too late.

Thanks in advance.

Trevor