False Positive on Format Factory

I have been using Format Factory to convert my mp4s to avis since my WLMM won't accept MP4s for some reason.  I have been using the program for some time with no issues until last week, when it started catching FF as bad and would remove it.  I would restore the program and mark it for future scans to ignore.  And it would happen again a few days later.  Yesterday, Norton once again caught it, but this time refused to let me restore it and demanded a restart to finish it's removal.  Format Factory was good and easy to use, but I have no been able to use it  since that day.

 

I would like to know what I can do about this, or if I am unable to use FF again, then if there is a good FREE, and SAFE video converter around that I can use.