Dear Asrock, Please forward this message, as more and people might get panic attacks in the future.

You need to fix that exe file in the next bios releases because my heart almost stopped when my brand new motherboard frozed on Post after running that crap in Windows 8.1.
Clearing cmos after bios update is not allowed(even manual states that), so i did not do it. I reseted the damn computer 10 times and nothing. The post stood there frozen without responding to my F2/DEL to enter uefi.
message was something like "To enter MEBx setup, pres ctrl + P" --- after pressing that, output is Entering MEBx... and freezes there. After restarting with constantly Ctrl+P pressed, it's still frozen. I was convinced your updater has cleaned or corrupted my bios right before it even tried to copy the new one on the flash.

I have windows 8.1 dual boot with Windows 7 and the windows bootloader belongs to win 7. What i believe happens, is your InstantCrap utility tries to temporary rewrite something between Post and Boot.

Solution was to remove the SATA hdd and uefi finally was accessible. I've reseted to default options and updated in uefi from stick this time.
Since that mishap, the A2 error code keeps displaying in the Post corner, despite all SATA hdds working just fine.