Ad. 1/2: I have Rampage Formula ( probably Win indicates it wrong ) and thought downloaded every lastest drivers from ASUSTeK Computer Inc. -Support- Drivers and Download Rampage Formula
but found that I didnt installed one utility - "ATK0110 driver for WindowsXP/Vista/Windows 7 32&64-bit"
Now I checked folder with drivers you mentoned and didnt found any older driver then 2009 - Asacpi.sys
was updated when that utility was installed. Hope it will help - going to test it.
Ad. 3: I tried it when changing to ESS5 from ESS4 with completly removing from PC and it was still happening.
I will write a post if it falls again or if it doesnt fall for atleast 4-5 days.
Thank you for help.