+1 for Chuck's not to not let your PC go to sleep with your interface running. That's generally a bad idea, even if your interface can survive it without a crash.

I tried the Windows sleep function years & years ago and it never did work right from the start.
 
I've never tried it since, and just forget about it all together.
 
Also, many advise 'No screensaver' at all - and in the Power Options, it's a good idea to change the settings for 'Monitor Goes To Sleep' and the other one there to 'Never'.
 
These small, simple changes can be enough to make a difference - maybe even be the difference.