This problem is being evaluated. It is likely the result of the testing and implementation of our new editor system. I will also be re-evaluating the signature settings to determine what the cause of the problem may be. Since it is Memorial Day Weekend in the United States, an answer may not be available right away. However, we will work towards figuring it out. You may want to try altering the image to either a .JPG or .GIF in the interim, or change the resolution and size. However, if neither options work, we will need to determine fully if this is an active bug and what the cause may be.