sonar.am.c!g24 causing issue with Big Fish game installation

I'm a loyal customer of Big Fish Games, but have experienced (for the first time) a Norton Security issue with the installation of a game after purchase.  The issue raised is with SONAR.AM.C!G24, and Norton recommends I don't proceed with the installation.  Big Fish say this is a false positive and that all their games are virus-free, but I'm really reluctant to proceed in case I end up compromising my security.  Can anyone help?