After Windows XP, microsoft default windows picture viewer CAN NOT play animated gifs. Only shows single frame still image... 
 Web Browsers and some Media Players like MPC-HC, MPC-BE etc... can play Gif, Swf... but it is better to use a free photo viewer. 
 Or "- Open Animated Gifs.htm" webpage... :) 


Free Image Viewers: 

XnView 
http://xnview.com 

IrfanView 
http://irfanview.com 

FSViewer 
http://faststone.org 


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Greetings from KOTUWA 
Ayubovan!
:]