(Currently using startx because lightdm and gdm both loop with no indication why in any log; one of the 3 terminal programs that don't segfault on startup, chromium because firefox launches to a crash dialog, alsamixer because the graphical mixer crashes, and the screen brightness slider because the brightness control keys stopped working.
All this and debsums finds no corrupted files except for one md5sums file itself full of binary garbage.)
@joeyh The most strange problems I've seen on my computers ended up being almost always because of hard drives. Like, when you don't have space things start failling in amazing weirdly ways. Once I had a drive that started getting corrupt sectors and I kinda saved it, at least it worked far longer than I expected, by running a full health check going over all sectors. That made the self protection mechanisms it has to mark sectors as invalid to trigger and the OS to work.