If you're looking for a PDF reader, it should be an .exe (Windows) or .dmg (Mac) from the official website, not a compressed .rar file from a random forum.
Always run a file through an antivirus or a site like VirusTotal before opening it. Download File Adocrobat.rar
His computer, usually fast, started stuttering as if it were processing a massive hidden task. If you're looking for a PDF reader, it should be an