There were problems with the gif file indeed.
Use any one of the following image instead of the one you posted. Double buffering
is not necessary.
The image has been corrected in photoshop. There were some redundant frames which may have been causing the flickering but the surprising fact is the image shows correctly on all image viewers but not in Java. So possibility of a java bug.
The first image is a bit faster, the second one is slower by 0.2s. Use any one.