No sound on WinXP guest (which used to work perfectly)

[fth0]

I see three candidates for problems:

00:00:13.168010 VMMDev: Guest Additions information report: Version 5.1.12 r112440 '5.1.12'
00:00:13.168139 VMMDev: Guest Additions information report: Interface = 0x00010004 osType = 0x00033000 (Windows XP, 32-bit)

You probably cannot use the VirtualBox Guest Additions 5.1.12 (GA) with VirtualBox 6.1.16. Start the guest OS in safe mode and uninstall the old GA. Reboot the guest OS without any GA installed and see if your problem persists.

00:00:03.403397 supR3HardenedErrorV: supR3HardenedScreenImage/LdrLoadDll: cached rc=VERR_LDRVI_UNSUPPORTED_ARCH fImage=1 fProtect=0x0 fAccess=0x0 cHits=7 \Device\HarddiskVolume1\Program Files\Lenovo\Bluetooth Software\BtMmHook.dll
00:00:03.403557 supR3HardenedErrorV: supR3HardenedMonitor_LdrLoadDll: rejecting 'C:\Program Files\Lenovo\Bluetooth Software\btmmhook.dll' (C:\Program Files\Lenovo\Bluetooth Software\btmmhook.dll): rcNt=0xc0000190

There is a Bluetooth software on the host that invades the address space of the VirtualBoxVM process and is probably forcefully removed by VirtualBox with unknown consequences. For a test, either uninstall the Bluetooth software or make it ignore VirtualBox. Please also post a (zipped) VBoxHardening.log file.

Generally, disable all power saving settings in both the host and the guest OS for your tests.

[Commodore]

VirtualBox Guest Additions 5.1.12 were leftovers from previous installation. I was able to go into safe mode to remove them, but after the reboot into normal mode, it hung again.
Another safe mode then, where I installed the corresponding latest Guest Additions. After the reboot, it also hung at the same point during the boot process (VBox.log and VBoxHardening.log from that session are attached).

Also, before the last boot attempt, I disabled Bluetooth Service and killed BTTray.exe (the only bluetooth-related process remaining) on the host machine. As far as bluetooth is concerned, the related software+driver(s) have been on the laptop since the very beginning, and apparently they never caused any problems. I checked for updates from Lenovo, but there haven't been any, though.

How do I make VirtualBox and Bluetooth ignore each other?

As for power saving settings, the laptop is plugged into AC power most of the time, without any special power savings for this mode of operation (i.e. everything is always on). The guest is also configered for "always on" mode.

[fth0]

The VBoxHardening.log indicates at least two software packages that invade the address space of the VirtualBoxVM process and are therefore considered adversaries: COMODO Internet Security and Trend Micro Eyes. Like in the case of the Bluetooth software, you can either uninstall them or make them ignore VirtualBox. I don't know how to do the latter, and VirtualBox cannot be made to ignore the threats (except by building VirtualBox from source yourself).

As far as bluetooth is concerned, the related software+driver(s) have been on the laptop since the very beginning, and apparently they never caused any problems. [...] How do I make VirtualBox and Bluetooth ignore each other?

After having discovered the additional adversaries above, this may not be necessary. For a test, simply get rid of all adversaries, and if the problem has vanished, you can reinstall and/or reenable them one by one again. Additionally, the VirtualBox hardening code was improved (and got more picky) over time.

00:00:03.571244 Guest OS type: 'WindowsXP'

00:00:03.633864 [/HM/] (level 1)
00:00:03.633865   64bitEnabled       <integer> = 0x0000000000000001 (1)

00:01:17.709633 VMMDev: Guest Additions information report: Interface = 0x00010004 osType = 0x00033000 (Windows XP, 32-bit)

In the VBox.log file, the middle line above caught my eye: While the guest OS type is configured as 32-bit and also recognized by the GA as 32-bit later on, somehow the 64-bit mode is additionally configured. If the guest OS is Windows XP (32-bit), execute VBoxManage modifyvm WindowsXP --longmode off while the VM is shut down, and test if your problem persists.

[Commodore]

Additionally, the VirtualBox hardening code was improved (and got more picky) over time.

Which is probably why at some point in the past after one of the VirtualBox upgrades the problems arose. Unfortunately I didn't have much time then to dig deeper. (In the last weeks I figured the last know good version was 5.1.12 r112440, but it's as though the VirtualBox upgrades in the past broke something specific, because going back to the good version resolves the boot freeze issue, but not the sound.)

Anyways, I executed VBoxManage modifyvm WindowsXP --longmode off (and checked WindowsXP.vbox for changed LongMode enabled="false", and the vbox.log has "64bitEnabled <integer> = 0x0000000000000000 (0)"). But the boot freeze still persists.

As for Comodo, it's also been here for ages, not causing any problems ever (also, the Windows 10 tablet, where I tried running the VirtualBox with the then same image of WindowsXP guest, has Comodo Internet Security installed, and it works just fine).

Trend Micro is another story - because I have no clue how it got there. The only antivirus software I used in the past were Microsoft Security Essentials and AVG (and I think I briefly tested Avast ages ago). Is it possible some other software used/uses TM as addon service? I guess I could start with renaming the file tmcomm.sys to something else to prevent it from loading.

[fth0]

Trend Micro is another story - because I have no clue how it got there.

Many so-called security softwares have a bad reputation amongst those who know, and tmcomm.sys is in good company. See the following German news report for some fun story about it: Trend-Micro-wird-vorgeworfen-bei-Windows-Treiber-Test-betrogen-zu-haben-4768607.html.