On the Forums Advanced Search page ( http://moodle.org/mod/forum/search.php?id=5 ) there is an option for "Posts must be newer than this". I've never gotten any results when I set this option.
Try this search:
This exact phrase: "Admin bookmarks"
Without a date entry, this search returns 34 results. Posting dates range from 2007 to 2012.
With "Posts must be newer than" set to 1 Jan 2011, I expect to get postings made in 2011 and 2012, but get no results.
Visvanath confirmed my findings in this thread over in the General Problems forum. He suggested I report my issue over here.