Oops. Copied the wrong link my second post. This is the right one:

thread.cfm?threadid=135621&messages=8

Can't be anything to do with my keyboard, as this isn't to do with what I type. I can see the HTML source - typed by other people - and it doesn't have Norwegian o's or Polish l's in it.

As far as I can see, Mudcat pages don't declare a character encoding. Perhaps they ought to.