Disqus happens to be one of the best comment systems for any blog, it provides a wide range of options both for you and your users. The best thing is that it can be integrated to almost any type of blogging platform. Recently some Disqus users mailed me and wrote on forums that their blogger templates began to act weird after installing Disqus. Some complained that the load time increased, the comments didn't appear below posts and many more.
Actually it happens to blogger users using highly customized templates such as mine. In this case while installing Disqus do not choose the option 'Blogger', just choose Generic code from the menu Admin > Tools .
Follow all the related instructions as it is and maybe you may loose some old comments.
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