we have posted a new installer (with the same build number though) to our website. users who face the problem illustrated in this thread should uninstall 5.1.0.0, download the new installer ("Virus TI Software Suite 5.1.0.0-2.pkg") and re-install again.
best, marc
Thanks, Marc, reinstalling this version (after uninstalling the previous version and rebooting) fixed my problem after upgrading to Yosemite.