If I run lyx as root it immediately core dumps. Not to me on my RH 6.1 box. Perhaps you did not set DISPLAY for root when you did this, and then lyx *always* does this: # lyx Segmentation fault (core dumped) # ls -l core -rw------- 1 root root 749568 Jan 21 09:41 core # rpm -q lyx lyx-1.1.4pre2-1 This error has nothing to do with root; it has to do with not finding where to display. Perhaps an xforms bug. Mate