Hi sankardeep v,
Do you have RadCompression enabled on your site? Do the weird characters disappear when you disable the compression? What is the size of the archives that you are uploading. Is it bigger than 4 megabytes? If so, you need to explicitly allow this in your web.config. Information on how to do this can be found here.
These weird characters may sometimes appear if there was server side error and the compression was turned on. Can you paste your web.config here, more specifically the handlers/modules declarations.
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