"Checksum error" when trying to download updates usually means there too many people trying to d/load from the server and it can't cope. Either wait and try later or possibly Bit Defender has alternative mirror sites you can try.
OnePlus 5 review
Stunning new film posters by Hattie Stewart, Joe Cruz & more
iPad Pro 10.5in (2017) review
Comment faire une capture d’écran sur un Mac ?