aVAST DETECTED FILE REP MALWARE
No, it isn’t a virus. It detects it like a virus because of its ad engine, which by the way, does not work anymore.
So download it with no fears in your heart.
The antivirus detected the Messenger Plus! due to its “sponsor”, which is a toolbar, recognized by security solutions like Adware. Pause your Avast, install Messenger Plus! with the option to install the toolbar disabled and activate Avast again.