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).