Posted as this was preventing me from installing an .MSI

http://www.windowsitpro.com/article/installation2/how-can-i-stop-users-from-installing-windows-installer-msi-files-for-removable-media-.aspx

With Windows Installer 1.1 and later, you can restrict users from browsing MSI files on removable media such as CD-ROMs and DVDs by performing the following steps:

1. Start a registry editor (e.g., regedit.exe).
2. Navigate to the HKEY_CURRENT_USER\Software\Policies\Microsoft\Windows\Installer registry subkey (create this subkey if it doesn’t exist).
3. From the Edit menu, select New, DWORD Value.
4. Enter the name DisableMedia, then press Enter.
5. Double-click the new value, set it to 1, then click OK.
6. Close the registry editor.
7. Log off and log on for the change to take effect.