Hi petr,
just some info for you. I can confirm that on my machine, disabling VT-x in the bios seems to have done the trick. In more detail:
For a baseline, I checked my BIOS settings, and in my particular bios, VT-d was disabled already (the default) but a setting called "Intel Virtualization Tech" was enabled. Anyway, with these original settings left unchanged, I attempted to install Avast Free (12.2.2276), and got the Blue Screen crash part the way through the install. So I rebooted into safe mode, ran the Avast clear utility to uninstall. Then I booted back into BIOS and disabled the "Intel Virtualization Tech" or VT-x.
Then, in full windows (normal mode, not safe mode) I re-ran the Avast Free installer. All went well. Did a smart scan, everything was fine. Then I ran a full system scan, everything went fine. Rebooted, no issues at all.
So it does appear that disabling VT-x does in fact stop the BSOD crashes. At least, so far for me, everything has been running just fine. Avast is working just fine.
Anyway, my specs, if it helps:
Windows 10 Home, 64 bit
Motherboard: MSI Gaming M7 z170a
CPU: Intel Core i7-6700
SSD (OS drive): Samsung 840 Evo 250GB
HDD (Data drive): Seagate Barracuda 5400 1TB
GPU: MSI Nvidia GTX 970 4GB
RAM: 16GB 2133 MHz Corsair
Soundcard: Steinberg UR12
Hope that helps.
Cheers
Justin