Nope, that didn't do it.
Doesn't matter now, I guess. It seems I didn't fix the video after all, as my monitor's just gone nuts. Instead of 800x600 res I've got about 900x700 and it's nicely bent outwards at the corners. Ah well - it was busted crap when I got it, anyway.
Um - as far as the other problem, I said NEdit was the only thing that did it and it's true that it's the only one that won't run but certain other apps give me similar type warnings - from gtk in those cases, mostly. Unfortunately, I didn't pay enough attention to get specifics.
Between my crap hardware and my software problems, I think I'm just going to take a break for awhile.