Uninstall ANY and ALL other compression/decompression applications (especially WinRAR). You will ONLY need 7zip from now on and forever. 7zip handles just about any compression/storage format you can even think of and is faster and better and ad-free and open source and integrates great with windows explorer.
Get it from this site (and not from a 3rd-party site like cnet or download.com or some such...)