Window Transparency Problem

Well I have been enjoying the Wavelab Elements demo. All my plugin windows have gone transparent, which I don’t want, and having followed the manual instructions I am rather confused. Preferences>Global >Display but the required info is not in the Tool Windows Section, or rather, where is it? Or have I got this all wrong?

A case of learning curve!

Thanks in advance.

Funny thing. The first time I restarted I was having the same problem. The second restart the windows came back???