XnView Software

How can I fix from this end? "Preview disabled" - I have never before come across how to enable/disable preview?

"could you post a screenshot?" Here are two resized Screenshots showing what results from the selection of Image>Adjust>

Windows 7. The problem seems to be in the View>Image>Adjust>Brightness/Contrast/etc. window not opening completely, not allowing any adjustments to be made.
My older version, 2.13, running on both Windows 7 & 8.1 operates properly on their machines, as usual. Ver 2.20 on Windows 7 has the problem ...

Installed upgrade to ver. 2.20 and 'Image' on menu does not show - File, Edit, View, (Image), Tools, etc. Commands associated with 'Image' not working either...