My anti-virus is blocking it for malicious software is this normal? It did it for TooManyItems from a different source as well.

It was McAfee web adviser btw

Where did you download the jar from.

As long as you downloaded the jars from either www.curse.com / www.curseforge.com or CB's webiste chickenbones.net Then it is safe to ignore. If you downloaded the jar from any place other than those i highly reccomend installing this chrome / firefox plugin http://stopmodreposts.org/