something similar happened on my Win 10 system which was stable and happily running ATI FireMV 2200 and 2400 video cards with the ATI drivers....when i updated Avast, i started having display problems....took 3 days of time to figure out that if i removed Avast, i could run the Video Cards i always ran before and keep my 4 monitor set up. i ruled out that this was from Win 10 updates, through an iterative process. i've now made a restore point, and will try reinstalling Avast, although i think somehow, the latest version available for download from the Avast site 07/04/2016, is what has been causing me the problem. i created a trouble ticket, but have not heard back from Avast.
i ran chkdsk /f /r C:
then rebooted
then ran sfc/ scannow which found some Corruption, but didn't correct some.
how does one get a Corruption free system without having to reinstall all the software?
why is Avast Free Edition causing these problems? (Page Fault in Non Paged Area atikmdag.sys)