I have the problem as well, and have been trying to work through the problem on my own since I have found no helpful feedback about how to resolve this issue.

- If you search a default installation of DotNetNuke, you find "SearchIcon" in the following files: ~\Resources\Search\Search.js and \Portals\_default\Skins\MinimalExtropy\skin.css

- $get("SearchIcon") always seems to return null/undefined, but there is no check for null before a var assigned the value return from $get("SearchIcon") is used later in the function initSearch (found in Search.js).

- It appears that initSearch 'skins' and adds event handlers to search controls... but I wouldn't quote me on that.

Today's my first day working with DotNetNuke and I find it extremely off putting that such a major issue hasn't been addressed (if it has, my apologies) and was part of there latest "stable" build.