On Es.wikipedia.org, a template is used on date-related articles (see URL) that somehow prevents the TOC from collapsing. Doesn't affect other articles or other languages, so I'm not sure exactly what's going on. Same behavior in IE7 and Firefox2. Error log for the page says that "toc has no properties."
Version: unspecified
Severity: normal
OS: Windows XP
Platform: PC
URL: http://es.wikipedia.org/wiki/23_de_abril