In my Win 7 Pro 64-bit machine, if I modify or clean-install (customized) Avast and check "Secure Virtual Machines", I get BSOD (blue screen of death) on reboot. Then I need to reboot with F8 and select Last Known Good Configuration.
I have run sfc /scannow twice - no problems. I have 16GB RAM, an i5 CPU and plenty of storage.
My Win 7 machine (a Dell Optiplex 7010) IS enabled for hardware virtualization, and I have run XP Mode a few times in the past just to see how XP Mode works (but not recently, and not while this problem has appeared). My good virtualization capacity is also confirmed by using the havdetectiontool from MS, and I have the correct virtualization settings in my BIOS.
By the way, in the Avast settings in its interface-Troubleshooting, I have "Enable hardware-assisted virtualization" checked - that is NOT the problem. Only turning on "Secure Virtual Machines" in the Avast installation is the problem.
Until recently, Avast was fine. This has been happening with Avast 11.2.2261.
I have now totally UNinstalled (also using Avast clear in Safe Mode) and re-installed (custom) without "Secure Virtual Machines", and the machine works.
Avast, once again, you have virtualization problems. You've been avoiding this topic for a long time, also because it means your NG isn't foolproof. What's the fix, finally?