I'm working with the Antivirus which came in the Symantec Client Security Corporate Edition (32 bit version, 9.0.0.338), and everything worked fine, but upon booting instead of loading the tray icon I found a %programfiles%\Symantec window open. This happens because the key in HKLM/Run called to (...)\Symantec Antivirus\VPTray.exe without any quote, so it never reached the correct folder. To solve this, one should add a destination folder without spaces in the command line, like: %systemdrive%\install\Applications\sav9\SAV9.MSI /qn INSTALLDIR="%programfiles%\SAV9" RUNLIVEUPDATE=0 REBOOT=REALLYSUPPRESS