Installed WB7 after uninstalling demo version.
All worked as expected.

While WB7 running I used Control Panel to change the Desktop color (only that value - nothing else). Did that as I couldn't see how to set just a plain color in WB7 (I'm sure there a way - I just couldn't see it).
Now the problems starts.

At next boot WB7 seemed to work (could scroll across skins and options etc), but when click "Apply changes" nothing happened.
Clicked "About WB7" and got this msg(***):-

"
WindowBlinds version : WindowBlinds 7.1 (build 90 x86)

WindowBlinds is not installed correctly on this PC.  If you did not reboot after installing WindowBlinds 7 for the first time, then please reboot and try this again.Your machine supports per pixel borders on WindowBlinds skins.

(LG W2242(Analog)) 1 is attached to NVIDIA GeForce 8400 GS   

Wblind.dll         2010/06/07 19:10:20
Wbsrv.dll         2010/04/01 21:40:56
SevenConfig.exe         2010/06/07 19:10:02
Wbload.exe         2010/04/01 21:40:18
Wbhelp.dll         2010/04/01 21:40:07
Wbui.dll         2010/04/01 21:40:05
Tray.dll              2010/04/01 21:40:19
Screen.exe         2010/06/07 19:10:43
"

I de-installed WB7 using Control Panel and reinstalled + reboot via Impulse.
Go to (***) i.e. Problem persists even after a clean install.

thanks for help.

ps Even my forum login fails now - had to get passwd resend to login to forum!