Hi, thanks for help, > Can you rebuild it with debugging symbols (ie. > swap the comment on lines 6 and 7 in the top Jamfile) > and rebuild it (jam clean; jam etc.) Yes just done: Program received signal SIGSEGV, Segmentation fault. [Switching to Thread 0x7f4f455d86e0 (LWP 11577)] 0x0000000000404315 in get_displays () at spectro/dispwin.c:630 630 if (disps[k]->crtc == disps[ndisps]->crtc) { (gdb) where #0 0x0000000000404315 in get_displays () at spectro/dispwin.c:630 #1 0x0000000000405768 in get_a_display (ix=0) at spectro/dispwin.c:961 #2 0x000000000040a741 in main (argc=1, argv=0x7fff4d608b68) at spectro/dispwin.c:3978 (gdb) quit But I found a workaround, reading your documentation, if I set ARGYLL_IGNORE_XRANDR1_2=yes it works. I know I should have read the doc carefully before, but do you think the programm can send a more understandable message before crash?? If I can test something to help or to find how make it run with xrandr1.2, do not hesitate to ask. Mike