I have a Windows 7 VirtualBox that I use for photo management (Lightroom, Photoshop Elements etc.). Given the recent decrease in price on the Nik Complete Collection after their purchase by Google, I installed it onto my VM but Silver FX pro and Color Fx Pro wouldn't start.

This was fixed by changing a config file so that it started up in Safe Mode. I changed three config files, and now the entire suite is happily starting.

The two files are:

C:\Users\USERNAME\AppData\Local\Google\Color Efex Pro 4\ColorEfexPro4.cfg
C:\Users\USERNAME\AppData\Local\Google\Silver Efex Pro 2\SilverEfexPro2.cfg
C:\Users\Tim\AppData\Local\Google\HDR Efex Pro 2\HDREfexPro2.cfg

I had to add the UseSafeMode section two both files, and they now both contain the following:

<configuration>
    <group name="INTERN">
        <key name="UseSafeMode" type="bool" value="1"/>
    </group>
    <group name="Language">
        <key name="Language" type="string" value="en"/>
        <key name="Region" type="string" value="en"/>
    </group>
</configuration>