Have a look at http://en.wikipedia.org/wiki/List_of_countries
More than half of the flags are broken images.
This is the same bug that I've reported millions of times before. People keep suggesting to use action=purge to convince the server to regenerate the image file. Well great, except doing that for all the broken flags on this page is beyond tedious. And besides, how is a casual reader supposed to do this.
This needs fixing quite urgently, especially seeing as it's been around for so long.
Timwi