Sorry for the late response I have only just signed up to these forums.
I have had many instances where this has happened. The easiest fix was the following and I hope it works for you as it did for me.
If this is happening in Vray 3.0
Make sure Sketchup is not running.
Go to C:\Users"username"\AppData\Roaming and Rename the “Chaos Group” and “vrayneui” folders to “Chaos Group.old” and “vrayneui.old” respectively.
Open sketchup and launch vray you will need to reconfigure some of the settings but once done should render as normal.