The problem is your light engine is failing. The part number for this is UX22201DR and is available for purchase with the following link. It runs $334 dollars and really is a part that needs to be replaced by a technician due to the complexity in tear down to remove it. Please take a few moments to rate my answer. Thanks...

http://www.partstore.com/Part/Hitachi+Ltd/Hitachi/UX22201DR/New.aspx

You need a light engine