Problem with startup `rc.local` script
I was using those commands for VirtualBox in rc.local, and I ran into the same problem.  I don't if this is the right way to do this, but it works for me.

I created /Library/LaunchDaemons/local.localhost.startup.plist containing the code below.  It runs the rc.local script once at start up.

&lt;?xml version="1.0" encoding="UTF-8"?&gt;
&lt;!DOCTYPE plist PUBLIC "-//Apple Computer//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd"&gt;
&lt;plist version="1.0"&gt;
&lt;dict&gt;
    &lt;key&gt;Label&lt;/key&gt;             &lt;string&gt;local.localhost.startup&lt;/string&gt;
    &lt;key&gt;Disabled&lt;/key&gt;          &lt;false/&gt;
    &lt;key&gt;RunAtLoad&lt;/key&gt;         &lt;true/&gt;
    &lt;key&gt;KeepAlive&lt;/key&gt;         &lt;false/&gt;
    &lt;key&gt;LaunchOnlyOnce&lt;/key&gt;    &lt;true/&gt;
    &lt;key&gt;ProgramArguments&lt;/key&gt;
        &lt;array&gt;
            &lt;string&gt;/etc/rc.local&lt;/string&gt;
        &lt;/array&gt;
&lt;/dict&gt;
&lt;/plist&gt;