The struggling bookseller now has to fend off a lawsuit from Microsoft over the Android OS in its Nook eBook Reader.

Microsoft (MSFT) today filed legal actions against Barnes & Noble, Inc.(BKS), Foxconn International Holdings Ltd., and Inventec Corporation in both the U.S. International Trade Commission and the U.S. District Court for the Western District of Washington over patents related to the Android operating systems on which its Nook eBook readers are based.

The fun part is where Microsoft says Barnes and Noble violated its patent portfolio with its Google (GOOG) Android OS: More