Solved. For mysterious reasons, the OS has suddenly changed the X daemon. Fro /var/Xorg.0.log" I noticed that instead of the correct "Module glx:vendor="NVIDIA Corporation" it has changed to "Module glx:vendor="X.Org Foundation". Reinstalled the driver, chimera OK. francesco ---------- Forwarded message ---------- From: Francesco Pietra <chiendarret@gmail.com> Date: Wed, Apr 14, 2010 at 12:19 PM Subject: X-server segmentation fault on launching chimera To: chimera <chimera-users@cgl.ucsf.edu> Hello: Having upgraded Debian Linux i386 squeeze release from kernel 2.6.30 to 2.6.32 everything works except X-server segmentation fault on launching CHIMERA, build 30282 of last March 29. I have successfully recompiled CHIMERA, last Apr 14 build, on the updated Linux release, to no avail. I need the experimental builds for features not included in the stable release (centroid trace in movie). To compare, another graphic program, GIMP, can be launched correctly. Below - between *** - the final part of "Xorg.0.log" reporting troubles. Before that, the log is identical to when X-server is working properly. Thanks for suggestions. francesco pietra ********* Backtrace: 0: /usr/bin/X (xorg_backtrace+0x3b) [0x80ada5b] 1: /usr/bin/X (0x8048000+0x5aa75) [0x80a2a75] 2: (vdso) (__kernel_rt_sigreturn+0x0) [0xb78b240c] Segmentation fault at address (nil) Fatal server error: Caught signal 11 (Segmentation fault). Server aborting Please consult the The X.Org Foundation support at http://wiki.x.org for help. Please also check the log file at "/var/log/Xorg.0.log" for additional information. (II) Power Button: Close (II) UnloadModule: "evdev" (II) Power Button: Close (II) UnloadModule: "evdev" (II) AT Translated Set 2 keyboard: Close (II) UnloadModule: "evdev" (II) ImPS/2 Logitech Wheel Mouse: Close (II) UnloadModule: "evdev" ********