Does the box contain info about the file that you're hovering over (eg bitrate, album name, artist, year etc)? I just use the default skin & the extended tooltips box is grey...if you're using another skin then the box could be yellow (just guessing here).

Try this: right click on the column header above search results > more options > untick 'extended tooltips'. If that doesn't fix the problem then post back with more info & a screenshot of the box would help