Same issue as bug 13778 -- the "fulltext" parameter in the default submit button doesn't get submitted by Internet Explorer if you hit enter in a text field.
As a result, fulltext searches from a form end up performing a "go" exact-match search on submission, which isn't what was intended and sometimes gives surprising results.
Forms intended to be fulltext-only need to include a hidden field providing the "fulltext" parameter so it will actually get sent.
Version: unspecified
Severity: normal
URL: http://en.wikipedia.org/wiki/Wikipedia:Village_pump_(technical)#Search_box_at_the_top_of_this_page