bizarre window placement / work area

[Trevor Callow]

Hi all,
New to list & XFce4, hope somebody can shed some light on the following
problem/problems or point me at the right documentation.

Background.
DEC Alpha1000a
-Fresh install of FreeBSD Alpha 5.1 -ok
-configured X on voodoo3
-twm works as it should
-download, compile & install the following 
xfce4-r2
xfce4-desktop-3.99.2_1 
xfce4-fm-3.99.2_1   
xfce4-fm-icons-3.99.2 
xfce4-iconbox-3.99.2 
xfce4-mcs-manager-3.99.2 
xfce4-mcs-plugins-3.99.2_1 
xfce4-mixer-3.99.2_1 
xfce4-panel-3.99.2_1 
xfce4-panel-themes-3.99.2_1 
xfce4-print-3.99.2_1         
xfce4-systray-3.99.2_1 
xfce4-toys-3.99.2_1 
xfce4-utils-3.99.2_1 
xfce4-wm-3.99.2     
xfce4-wm-themes-3.99.2
-all is well no errors etc

Then the problem.
XFce4 started, loads and looks quite nice,
but the work area is displaced up by
2/3 of the screen ie. all windows can not be
moved to the lower 2/3 of the screen and are 
truncated. This happens in all 4 work areas.
When displaying a new window they appear either off 
the top of the screen or only the bottom section 
is partially visible. 
Have tried various user settings but alas to no
avail.
Otherwise all else appears to work quite well ie.
panels, consoles etc.

Thanks

Trevor Callow