The 'ADDUSERS=0' command line option is necessary for silent installs and suppresses the popup window asking if you want to add new users.
Below is an example of the command line install: msiexec /qn /norestart /i 'NComputing vSpace_L-4.9.5.11.msi' AGREETOLICENSE=yes ADDUSERS=0 DELETELICENSE=0 NComputing MSI Installer and Uninstaller Options: Note: depending on version of installer, you may need to use the NComputing Cert or the ZeroDesktop Cert. You can use vSpace 6 / 8 MSI install files from the Windows command line to silently install vSpace without user interaction.
