It only seems to be a problem if you use the unified search (the search box in the upper right corner). When searching using the basic or advanced search dialog in the modules, the problem does not appear.
The problem appears to be that we are escaping the search text when we should not. In the App_MasterPages folders, replace:escape(frm['<%= txtUnifiedSearch.ClientID %>'].value)withfrm['<%= txtUnifiedSearch.ClientID %>'].value