PC Defender 360 is a Fake Antivirus. It displays fake warning messages to push users into buying a license. It is from the same familly as: Multirogue Defender and PC Defender Plus
The rogue is closing legit software. You can register by entering the following serial code:
xOxZxLxWxIxTxFxQxCxNxYxKxVxHxSxE (manual registration).