I would suggest you to start again with as simple config as possible - without fancy motd, cron, colors, and other shit that is of great value for some unknown reason for many people. Your server tries to reach a part of the memory that he is not allowed to, probably because of badly formatted (or too long) string, that he is supposed to print. Review your configs and search for any odd characters and remove them. It might be a bug in q3. On the other hand, i always check the memory of computer, that starts to kill processes with sig 11. Memtest86 or similar should do the trick. Gdb debugging is the last thing you can do. If you do it right, you have 100% chance for finding the source of the problem, but without q3 compiled with debugging options it is going to be a tough piece of work. If it's the only way, though, go to ioquake3.org, get the sources and compile them, adding -g and -ggdb flags to CFLAGS in Makefile beforehand. Then you'll be able to attach gdb to running q3 process or run q3 directly in gdb. Ioquake3 does not support punkbuster, but is more stable (less bugs) than 1.32c.
Good luck.