What is addon.exe? Should I remove it?

addon.exe is an executable file that starts a malicious process, launches certain parasite components or runs a destructive payload. Even if the addon.exe file does nothing suspicious, its presence indicates that your computer is infected with a particular threat.
The addon.exe file is installed and used by Mega Antivirus 2012.
You have to delete the addon.exe file immediately after you have found it. The parasite will continue to violate your privacy and harm your computer unless addon.exe and all related objects will not be completely removed from the system. If you have difficulties erasing the file consider using an anti-spyware program.
Please note that the addon.exe file actually may be a fully legitimate part of the operating system or legitimate software. Often parasites use files with unsuspicious names, but malicious functionality. You should always carefully check the file before deleting it. It may not be related with malware, but can be required by your essential programs to work properly.