Many modern malware strains are designed to be stealthy. Your PC could be part of a botnet or logging passwords without visible symptoms. Antivirus software may miss new variants for weeks.
Temporarily disable your antivirus software. Sometimes, these programs can interfere with the installation of patches. sony vegas pro 13 patch khg download install
Given the potential risks of patching, consider if an official update is available: Many modern malware strains are designed to be stealthy