This is a pain.
I need (probably, but it'd be a good start) to 'offline edit' an XP machine's registry, to stop it always booting to Safe Mode GUI (even when requesting Safe Mode with Command Prompt, via F8). This is because the keyboard (and mouse) are not working by the time I get into SM. They work in BIOS, and during the F8 "choose how to boot" stage, but stop responding (evidenced by classic NumLock testing, at least for the keyboard) once past the F8 (optional) stage. Regular, uncomplicated USB plug-ins (hardware too 'new' to have PS/2 on backplate... pity, as I've dug up a PS/2 keyboard right here that probably works, before realising it was not the solution). Mouse only ever gets chance to prove itself in firmware diagnostic screen from F12 boot-up (where it, or keyboard, can navigate the proprietary UI that uses), but that seems good enough to me.
Ruling out hardware issues, the machine worked fine before the reboot, swapping USB plugs to different sockets gives identical working/non-working responses, both items are uncomplicated enough to be fully supported by anything maybe Win98-era onwards. Mouse is optical, not ball, but of the kind that is hardware-agnostic to anything that would work with USB-ball, and the light on further proves USB sockets are powered.
I think, therefore, I need to regedit (command line, if necessary) the "force reboot to (GUI) Safe Mode" option that I think is to blame for this, or else edit some .INI item/similar (less likely, but currently also unable to do). No XP disc here (probably should be a recovery partition, given the original manufacturer, but can't access that so not sure if it survived past reinstallations), all my old regular bootable discs are half a day's travel away and may also have 'expired' as I haven't used them for a while and originally burnt them to CD-R(W) well over a decade ago, and the places where I would take the trusted Third Party Recovery Discs from seem to be on the wrong side of linkrot/domain-expiry.
Probably could burn some bootable-CD anew (maybe bootable-DVD, though all there is in the immediate vicinity on a working machine is a CD-R(W) drive, anything more is a pain, and I'd have to go get a new USB drive to make that bootable). But I'm a bit wary about some solutions, or even if they do what I think I need them to do. So any suggestions before I escalate my own efforts and resort to jumping in the car would be appreciated. Too much cruft and unrelated and (probably) unreliable/untrustworthy linkage in my current 'refresher' search for Recovery Discs, etc, and it seems like my old favourites may have become unsupported, ruined or maybe changed their names.
Next best option is to transplant the drive and mount it into another machine (ideally as a secondary drive, rather than a 'mind transplant' and deal with the fuss of a whole-body-transplant situation annoying Windows), but I'm limited to certain hardware without (again) half a day's unscheduled travel, possibly still on a hiding to nothing if I can't do the 'offline' tweaks how I think I need to do them or get it to be happy in a PS/2+SATA combination. (Might be that my PS/2 stuff is only IDE, etc.)
Further fall-back option is to work out why the "USB-safe" driver is failing, given normal-mode drivers (if different!) happily worked right up until this instance, and corruption of the driver used for both, right upon this moment, seems unlikely. Also, still needing a way to fix that, if that's what needs fixing.
For the record, yes, I know it's XP (a perfectly sane OS, for the use it's being put to, and you don't want to know the fuss we'd have if we wanted to change it). I still run XPs (and earlier) of my own, but not right here, right now or sufficiently the same setup to just guarantee I could migrate things over (because of this or in general). (Even if I could spare more than a temporary repurposing.)
And the Safe Mode-forcing seems to have been done by the AV program (token, given it's not connected to anything, but you get OS complaints without one) when we were uninstalling it in preparation for reinstalling it to convince it to accept the new (Free) licence that covers its operation. (Don't know why this happened. I know for a fact that this cycle of annual renew has been working since 2017, a kludge as it may be.)
Just putting this rather old-school problem out there, for entertainment purposes, even if nobody is quick enough to shortcut my fall-back-fall-back options that I'm still holding in reserve...