VERR_VMX_NO_VMX on VB 4.3.18

[Ramshankar]

I think my problem may be caused by my security software: Kaspersky Internet Security 2015. The software installs a driver (klhk.sys) that uses hypervisor technology - the Windows VMM. Another writer in a different user forum discovered that the same driver prevented him from adding Hyper-V to Windows 8.1.

I'll have to do more poking around to be sure about this, but I believe I'm headed in the right direction.

That makes more sense. It is entirely possible for anything to hijack VT-x on Windows with VirtualBox as by default, VirtualBox only claims it when it actually uses it when executing guest code and then relinquishes it when it gives up the CPU for the host operating system (this happens several thousand times a second while running a VM). This is to play nicer with other hypervisors like VMware, but takes a tiny performance hit.

[mpack]

Yep, AV is about as effective a DoS attack as any deliberate example!