Weirdness with Firefox has been tentatively diagnosed as actually nothing to do with software specifically, but in fact a bad memory card (or possibly bad slot on mobo). I say "tentatively" because I'm not eager to re-create the original conditions by re-inserting it and doing what I was doing when the problem started, but the problems I was having with I/O errors while trying to repair the Windows installation stopped* as soon as I took it back out, so I'm considering that suspiciously encouraging (...o.o) even if it's not conclusive.
* - After about a kazillion attempts to both "upgrade" and "repair", including reaching a point of desperation where I reformatted the second drive (which I had been meaning to get around to doing anyway) and tried starting from scratch. When this didn't work is when I stopped suspecting the hard drives (which I never seriously had anyway) and started thinking "well, what else did I recently change besides trying to upgrade to FFX 1.0.3 and the latest Zone Alarm?" I'm lucky it managed to doggedly continue on the same "upgrade" attempt and that it finally took, once the problem with errors copying all the files got resolved, because it meant my settings and programs (most importantly, the single user and its "my documents") were intact; although I had backed up everything onto C: before starting this enterprise, of course I lost that when I was at the last-ditch of reformatting it and installing a fresh shiny Windows.
(I think I splat now, after this download finishes.)
edit: Oh, if you're wondering how "Firefox crashing" led to "repair Windows", there's more than one step there. One of the times it crashed was weird and near-fatal - it generated a stop error and when the computer restarted it had forgotten or corrupted my video card drivers. It was stuck at 800x600 and 4 colours (!). This was just a bizarre symptom though. When I was fiddling around with installing Zone Alarm and it was complaining about being unable to validate dlls I should have probed a little more thoughtfully, I think. But in any case, it got into a cycle of corrupted files (as far as I can tell) and there came a point where I couldn't successfully boot Windows anymore (well.. once or twice. It was weird. I was trying too many things at once, really.). Hence the repair or upgrade attempts. I'm not *that* crazy. Heh.
* - After about a kazillion attempts to both "upgrade" and "repair", including reaching a point of desperation where I reformatted the second drive (which I had been meaning to get around to doing anyway) and tried starting from scratch. When this didn't work is when I stopped suspecting the hard drives (which I never seriously had anyway) and started thinking "well, what else did I recently change besides trying to upgrade to FFX 1.0.3 and the latest Zone Alarm?" I'm lucky it managed to doggedly continue on the same "upgrade" attempt and that it finally took, once the problem with errors copying all the files got resolved, because it meant my settings and programs (most importantly, the single user and its "my documents") were intact; although I had backed up everything onto C: before starting this enterprise, of course I lost that when I was at the last-ditch of reformatting it and installing a fresh shiny Windows.
(I think I splat now, after this download finishes.)
edit: Oh, if you're wondering how "Firefox crashing" led to "repair Windows", there's more than one step there. One of the times it crashed was weird and near-fatal - it generated a stop error and when the computer restarted it had forgotten or corrupted my video card drivers. It was stuck at 800x600 and 4 colours (!). This was just a bizarre symptom though. When I was fiddling around with installing Zone Alarm and it was complaining about being unable to validate dlls I should have probed a little more thoughtfully, I think. But in any case, it got into a cycle of corrupted files (as far as I can tell) and there came a point where I couldn't successfully boot Windows anymore (well.. once or twice. It was weird. I was trying too many things at once, really.). Hence the repair or upgrade attempts. I'm not *that* crazy. Heh.