Shift + F4 no longer working in application

[TerryJ]

I cannot track this down.  Shift+F4 is a keyboard shortcut which I was 
using in OpenOffice.org until recently.

It is still assigned in the application settings but is ineffective.  I 
cannot find it in the Xfce settings (keyboard or window manager) and it 
seems to have no effect in the desktop.

What could account for the keybinding no longer working?

-- 

Regards, TerryJ

Using Xfce 4.3.99.1 (Xfce 4.4 RC1) on PCLinuxOS 0.93 www.revivalcentres.org