I get a routine digital signature error from Norton on this version (and I think a previous version). When that screen comes up, there is an option to allow. Also, you should disable data protector under Antivirus settings during install, and, ideally exclude all the exe files. I am still having some issues with .42 saying it is blocking file changes when I use the tagging operations. Not sure why, but it isn't clear that it is actually blocking them. Anyway, the above should help, if like me, you insist on using Norton.