Windows 7 x64, Asrock Z77 Extreme 4, every driver installed and updated, latest bios installed on the mobo. Sometimes, when I hibernate my system, my system hangs on a black screen after the "resuming windows" screen. No HDD activity led, no signal on monitor, nothing works, not even the reset button, and I have to keep the power button pressed for 5 seconds and try again. Sometimes it works on the second try, but not always. There is nothing in Windows Even Log. Windows was recently reinstalled too. Why is this happening, how do I troubleshoot it, and how can I fix it? I followed the sticky and generated some trace files but so far hibernation has not failed yet, so I don't know if they are useful. Also, the system hangs on resume when using sleep and even Intel Rapid Start. I am getting desperate, I hope someone can help with this. Other hardware: Gigabyte GTX560Ti, i5 3570K, 8Gb Corsair DDR3 1600Mhz, WD Blue hard disk as system drive. Nothing is overclocked. All drivers and motherboard bios are updated.