Per Ant:
It seems after a couple weeks of nonstop uptime (no hibernation and
sleeps too; highest was 22 days!), my very old updated 32-bit Windows XP
Pro SP3 will start misbehaving. I would need to start exiting stuff
because softwares were not responding (Explorer, SeaMonkey, Trillian,
cmd.exe, etc.) correctly. Eventually, this won't work anymore, and I am
forced to reboot.

What about the rest of you guys? Thank you in advance.

I am sure it is overkill, but I have gone over to re-booting one of my
machines (in a remote location where I would have to drive to reset it)
automatically every morning at 0200.

Does not seem to me like there has been any cost during the couple of
years I have been doing this: schedule the reboot and forget about it.

On all my machines, I have BIOS set to automagically re-boot the machine
if/when power is removed/restored so, for those machines within easy
reach, there is always yanking the power cord as a last-ditch move if
the three-finger salute does not work.
--
Pete Cresswell