If I click through 'tags' I can bring results up no worries - they are many more issues for both of these. (So the short answer is use tags, or use google, but maybe I want to search on an error message?)
Searched on mac with firefox and safari. Reproduced on others' macs also.
As an aside: Does the tag-notification system work off this?
This isn't really answering the question, but rather suggesting an alternative which has been suggested to others previously for you to try which should get you more relevant results:: just use google.
Punch in whatever search terms you want into google, and append site:support.bioconductor.org at the end of your query.
It might even make sense for the site's search bar to be rewritten to do that by default ... turns out that if Google is allowed to index your site, it's hard to beat them at the whole search thing ... :-)