Or, the one where one finds weird things happening with fonts in various parts of the operating system. (So a slightly public note to self in case it happens to me again has arisen.)
As per the similar http://forums.mozillazine.org/viewtopic.php?p=2933984, I was having issues with Internet Explorer 9 and Firefox 4 in Windows 7 (64-bit) making most instances of Arial Regular turn Arial Bold since pretty much the day I upgraded from versions 8 and 3.x respectively. The mental note to myself (and in case any other people else get this) being that even though the forum thread is nearly four years old, the same idea of overwriting the fonts folder with the same errant font files (that is, copy out of
C:\WINDOWS\FONTS\ to another folder, and then back to
C:\WINDOWS\FONTS\ again; moving not required and probably, I suppose, not a good idea in case someone wants the fonts in the very short meantime) worked. Oddly, the Chrome 11 beta channel I am using was not affected, for whatever reason (which I assume was because of some different way fonts are used).
(Which reminds me: I need to finally write up how I got my home network's PPTP server working in Ubuntu to mitigate Firesheep and Firesheep-like attacks, nervously using unencrypted public VPN servers having finally pushed me to do it.)