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yekim54 - Where did you get the download - this is the 'official place' ==>>
calibre - Download calibre
If no luck with main site, try second alternative (it uses https) - your ISP may have cached a corrupt download, https should overcome that.
PS : rather than Revo uninstaller which doesn't handle 64 bits apps and may indeed trash your configuration directory - I suggest a lightweight registry cleaner such as CCleaner.
BR