Reply: A2update.dll is one of the files of Emsisoft Anti-Malware. In general, it will not be deleted unless it encounters a powerful destruction program that destroys Emsisoft Anti-Malware. According to your description, I think your machine has a vulnerability and is invaded by a malicious program which destroys the internal software. After the malicious program invades the operating system, the first step is to destroy all the anti-malware software in the system, so no matter how you repair the anti-malware software, It will eventually be destroyed again.

I suggest that you first upgrade your operating system, install all the vulnerability patches. Then uninstall the anti-malware software, re-install it and upgrade to the latest virus database. Finally detect and remove the malware in the system.