REAVIS is a computer program designed to prevent computer system infections, and improve computer security and stability. It has a four-wall defense protection system that operates simultaneously, different from that of commercial programs. Henceforth, REAVIS can make a revolutionary impact in the global computer security. REAVIS was developed using AutoIt compiler program and was tested with three commercial programs in uninfected and infected computers both installed with the trial version of Windows 8. The infected computer was only used to test if the antivirus can block malicious sites in such condition. The first wall, Malicious Site Blocking, used the Windows internal command in blocking confirmed malicious sites in the watch list of Microsoft and other trusted sources. This method is absolute and does not exhibit errors. It enabled REAVIS to effectively block all malicious sites in this study including the top 10 most dangerous ones. The second wall, Malicious Process Blocking, subdivided into two barriers. The first blocked malicious processes by consistently terminating all the listed malicious processes; and the second blocked all executable files that included malware. This explains how REAVIS successfully blocked 150 malicious processes. The third wall, Autorun Virus Prevention, eradicated the system’s Autorun virus root source and established immunity, preventing malware infection. The fourth wall, Direct Malware Deletion, removed the malware root source to avoid malicious activities. To complete a six-second computer scan, REAVIS consumed only 13% of the CPU resources. The four-wall defense attests that the REAVIS proactive security management surpasses the existing antivirus programs.