I didn't take the HDD out of the notebook, but I ran several diagnostics to both RAM and HDD, taking several hours. No issues found, and SMART reports also said everything is fine.

Anyway, I consider this solved. Elenarie's suggestion worked, as long as I was able to create that USB install media. Lots of bad luck there, but I was able to find one PC shop here which also let use their computers (15 THB for one hour, pfft, that's like 38 cents per hour or something) and had a reasonably fast internet (15Mbps or so according to speedtest.net). The Win 8.1 USB media got created without issues there, and it installed without issues on that notebook (first removing the Linux Mint partitions from there with the Linux Mint USB LiveCD).

As soon as Win8.1 was installed, it asked whether I want to upgrade to Win10. What the heck, I said yes, so now it is downloading that. Let's see how that goes, but that's a story for another day and thread... (if Win10 has some issues on that notebook, fine, I re-install Win8.1 back).

Yeah, that beer...

Congratz on having that issue solved somewhat, timppu. If you have issues with Windows 10 drivers, try using some Windows 8.1 ones or even 8's/7's. Windows 8.1 is more friendly (and bugless) at the time than 10.

Good-Luck!

REDVWIN

congratz. i'm surprised you found half-deccent interwebz in thailand. that country still sounds like a blackhole in terms of broadband internet.