Thanks a lot for helping however it still does not start even with a full system upgrade, kernel 188.8.131.52
Fyi glxgears & glxdemo are ok and glxinfo informs that
direct rendering: Yes
Gallium 0.4 on ATI RV410
Shading language: 1.20
So I tried to isolate Cairo and installed cairo-clock which runs fine !
It works with x86_64 on another PCs, it might be because the target PC is too old, without a strong GPU ?
I give up.