VM will freeze around 30 seconds after starting

[Sam9978]

Yesterday I made a VM for CentOS and attempted to start it and it all looks fine but will completely lock up around 30 to 60 seconds or so after starting the VM or if I try to interact with the VM in any way it will lock up immediately. And the only way to terminate the program is to kill it in Task Manager.

I tried running some other VMs I have that host Windows 10 and XP and which worked fine the last time I ran VirtualBox but they are now doing the same thing.

I'm running VirtualBox 6.0.10 r132072 on a Windows 10 Pro 1903 that is fully up-to-date. I have not installed any programs since the last time I ran VirtualBox and it was working correctly. I've reinstalled VirtualBox but that didn't seem to make a difference.

I've attached the log file from the CentOS VM and can attach some from the other VMs as well if needed.

Thank you for your help!

[Sam9978]

Oh, and I forgot to mention that sometimes when shutting down or restarting Windows I'll get a VirtualBox memory error. I'll try to make a note of it the next time it happens if that would help.

[scottgus1]

Your log shows the usual Windows 10 problem:

00:00:02.019720 HM: HMR3Init: Attempting fall back to NEM: VT-x is not available
00:00:02.067400 NEM: WHvCapabilityCodeHypervisorPresent is TRUE, so this might work...

See I have a 64bit host, but can't install 64bit guests Carefully go through each command in the 2nd & 3rd posts. Based on my perusal of successful fixes for this problem, the silver bullet appears to be the "bcdedit" command & complete power-down in post 2 point 1.

[scottgus1]

You also have some wiggle room on the number of processors you can give the guest:

00:00:02.019314 NumCPUs <integer> = 0x0000000000000001 (1)
.....
00:00:02.593131 CPUM: Physical host cores: 4

If you don't plan to run a lot of guests at once you could give this guest 2.

[Sam9978]

Based on my perusal of successful fixes for this problem, the silver bullet appears to be the "bcdedit" command & complete power-down in post 2 point 1.

Yep, that was it. Even though I already had all the Hyper-V stuff disabled running the "bcedit" command fixed the problem. Thank you so much!

[Sam9978]

You also have some wiggle room on the number of processors you can give the guest:

00:00:02.019314 NumCPUs <integer> = 0x0000000000000001 (1)
.....
00:00:02.593131 CPUM: Physical host cores: 4

If you don't plan to run a lot of guests at once you could give this guest 2.

I currently have to run 3 VMs simultaneously so that's why I have it set to 1 CPU. But if I ever do run it on its own I'll definitely change that. Thanks for the tip.

[scottgus1]

Glad you're up and running!
If your guest is working fine on one processor now, do like I do: follow the "If it ain't broke don't fix it" paradigm.

[Sam9978]

So I figured out it was the Windows Sandbox feature that came with the Windows 10 1903 update. The update must have enabled the Hyper-V features so that the new Sandbox feature would work but for some reason, the Hyper-V features did not show as being enabled (I'd specifically disabled them a while ago due to some other problems they were causing) so I didn't put 2-and-2 together.

[scottgus1]

There's probably the official "Hyper-V" setting that would allow you to run virtual machines, and the "Sandbox" feature that uses the same substructure that "Hyper-V" uses, and they both turn on the substructure, which hogs VT-x. The 3rd post in the "64-bit guests" tutorial has a list, and the list just keeps getting longer....