This is something we are working out with Norton, and is not an actual cause for concern. It affects Windows 7 and 8 users, and is a result of other Norton users flagging our software as unreputable. We will hopefully have those files cleared with Norton shortly, and this issue will dissipate.
Not all Norton/Soundtoys users are experiencing this, and the files which it affects vary from person to person. You may not even see a message at all. For now, you can ignore that error, manually remove the files from the quarantine, and proceed with the installation.
For more information on this message, please click here.