Thanks. No joy yet.
I also downloaded [link|http://www.proximasoftware.com/fontexpert/|Font Expert 2005] ($49.00?!?) and had it look at things. It didn't find any problems with the fonts themselves, but said some of the mappings weren't quite right.
TweakUI -> Repair -> Repair Font Folder and rebooting didn't change anything.
I guess it's not the Fonts then, but some other problem.
I looked at getting the latest ATI driver, but it wants .Net 1.1. (Luckily, that's already installed, but I'm not sure I want to go that route at this point.) Also, the T41 seems to be running an IBM-customized version (ati2mtag.sys 18.104.22.16825), but I can't find the file that has the IBM name tacked on in the version at the moment. I don't see any way to revert to the previous version, but I'll see if I can do that...
Hmm 21 hits on [link|http://groups.google.com/groups?q=22.214.171.12425&ie=utf-8&oe=utf-8&client=firefox-a&rls=org.mozilla:en-US:official&sa=N&tab=wg|126.96.36.19925]. Most of them seem to be related to games, but I know Office can bring out bugs in display drivers...
One of the threads mentions finding a problem by using [link|http://www.kensalter.com/fsautostart/|FSAutoStart] - apparently another utility was causing the problem in his case.
This evening I'll try a different driver (there are some [link|http://groups.google.com/group/nz.comp/browse_thread/thread/7d5af7669c411e82/20a607f96d8e3a60?lnk=st&q=188.8.131.5225&rnum=1#20a607f96d8e3a60|reports] (last post) that Catalyst 5.4 (184.108.40.20625) has problems that earlier versions don't and that 5.1 may be one to try). Since I don't run games, and since it just started happening recently, it sounds like a reasonable approach.
I'll report back when I know more. Thanks again.