Found the culprit; ATI catalyst AI needs to be disabled, then the launcher works.
(seems the Cat9.1 AI was a problem for other users of DCS:BS)
I'm using Cat9.3, as I have an AGP X1950pro gfx, non-dx10 capable.
(And I was administrator already, but ty for the suggestion Distiller)
edit: I found it's enough to set Catalyst AI to 'normal' and keep it on, if one wants to.
Still the cat9.x drivers have the 'white menu' problem;
no known workaround but rolling back to cat8.x drivers
What I first thought was some fancy designer menu with only icons and no text, was actually a known bug.
(the menu is still useful, and that is all the effect I have seen so far from cat9.x)
Same issue as before using catalyst 10.2 and DCS:BS game update 1.0.1c (english) and 1.0.2
Setting Catalyst AI to 'standard' lets the launcher run, but it still has a *white* screen instead
of the normal menu background.
(one can learn the icons meaning by trial & error, or looking in the manual)
edit: the buggy white menu only appears in single play, for multi-play the menu is normal
with a helicopter picture and text for the buttons.