virtualbox.org

When I turn on a virtual machine with Linux Ubuntu with a windows 7 as host, it gives an error and asks me to turn it off. It manages to start the operating system but after a few minutes it freezes. The only error it gives is that I sent the log to the community forum.
Attached the error log.
I hope you can help me.
I tried to clone it and run it on another disk and it gives the same error.

00:00:03.230213 Console: Machine state changed to 'GuruMeditation'
00:00:03.230316 !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
00:00:03.230316 !!
00:00:03.230317 !! VCPU0: Guru Meditation -4000 (VERR_VMX_VMXON_FAILED)
00:00:03.230357 !!
00:00:03.230362 !!

VERR_VMX_VMXON_FAILED means that something else is using VT-x. On a Win7 host this will be your chosen antivirus software (Avast).

p.s. We only need one copy of the VM log (your ZIP contains 3 copies).