Hi,
Attempting to run VMs with virtualbox.
VirtualBox Manager launches OK.
VM (linux, win) launches window but freezes - no mouse keyboard. Cannot exit, nor return to the Host machine. Only recourse is to poweroff.
The VM logs are empty.
journalctl gives -

_john@john-picasso ~ [0|1]> journalctl --since "2024-05-6 15:40:00"|grep vbox
May 06 15:40:56 john-picasso kernel: vboxdrv: loading out-of-tree module taints kernel.
May 06 15:40:56 john-picasso kernel: vboxdrv: module verification failed: signature and/or required key missing - tainting kernel
May 06 15:40:56 john-picasso kernel: vboxdrv: Found 16 processor cores/threads
May 06 15:40:56 john-picasso systemd-modules-load[219]: Inserted module 'vboxnetadp'
May 06 15:40:56 john-picasso kernel: vboxdrv: TSC mode is Invariant, tentative frequency 3792551313 Hz
May 06 15:40:56 john-picasso kernel: vboxdrv: Successfully loaded version 7.0.16 r162802 (interface 0x00330004)
May 06 15:40:56 john-picasso systemd-modules-load[219]: Inserted module 'vboxnetflt'
May 06 15:41:07 john-picasso systemd[1136]: Starting vboxclient...
May 06 15:41:07 john-picasso systemd[1136]: Started vboxclient._

All help appreciated,
JJ

Complete freeze > first thought is running out of resources. How much RAM does the host system have? How much RAM assigned to the VM?

Host system has 32Gb RAM with 20Gb assigned to the Windows VM.
The linux VMs have 8Gb assigned and they too freeze the system so I think unlikely that the cause is running out of resources.

All these VMs worked perfectly before the update to Vbox 7.0.18

Since I can't replicate, you will need to get the (full) journal output from the freeze

Nothing visible in that log as to when virtualbox was started, but 3 things do stand out for your install, biggest is the huge amount of errors/warnings/failures with syncthing (not part of KaOS), the use of a broken sddm theme (sleek?) and the use of a probably not ported (to plasma 6) widget (com.github.prayag2).
What is the output of pacman -Qi syncthing ?

Your help much appreciated.

Name            : syncthing-bin
Version         : 1.27.3-1
Description     : Open Source Continuous Replication / Cluster Synchronization Thing: binary.
Architecture    : x86_64
URL             : https://syncthing.net/
Licenses        : MPL2
Groups          : None
Provides        : syncthing=${pkgver}
Depends On      : None
Optional Deps   : None
Required By     : None
Optional For    : None
Conflicts With  : syncthing
Replaces        : None
Installed Size  : 22.37 MiB
Packager        : Unknown Packager
Build Date      : Wed 21 Feb 2024 16:27:23 GMT
Install Date    : Wed 21 Feb 2024 16:27:42 GMT
Install Reason  : Explicitly installed
Install Script  : Yes
Validated By    : None

I have removed SDDM theme Sleek and prayag2.
Still getting the same freeze.
JJ

Glad to see it is self-build, and not installed from some unsupported repo 🙂

Just to make sure it is not some hardware failure that coincides with the vbox update, can you re-install the 7.0.16 virtualbox packages from your var/cache/pacman/pkg and see if no more freeze?
That would mean using pacman -U for virtualbox-qt5 & virtualbox-modules.

And as a note, please use code tags for cli output (enclose with 3 backticks ```), done for you twice in this thread.

Problem Solved.
The motherboard BIOS was the problem.
ASUS A320I-K bios 6210 Sept 23 worked with 7.0.16 virtualbox happily but froze with 7.0.18
Flashed new bios 6223 Mar 24 and 7.0.18 is now working.

Many thanks for all your help.
BTW Kaos now also runs far better thanks to your suggestions from the journal.
JJ