Sleep in windows isn't a bad thing as long as your hardware is cooperative. It can cause some issues when overclocked but overall it's a nice feature if you need or want to use it. I currently use it kinda. I set sleep to never in windows but have a sleep button on my keyboard. When I want it to sleep I press the button and it sleeps.
I didn't see anything posted as far as your troubleshooting to solve the issue.
Your issue can also be caused by your CPU overclock as it's a common thing once you push SB's up there. Did you have to enable CPU PLL overvoltage? It's a hit and miss thing which will vary from cpu to cpu <> mb to mb <> and the cpu/mb combo.
Try dropping your overclock down and see if it cures the issue or not. If it does the choice is yours on the to sleep or not to sleep decision. I choose to sleep most of the time, but shutdown works if you got a really fast rig anyways!...SSD for the win
