I took Iddo's advice and rebuilt with no optimization (no -O flags of any sort). '-g' is still in there. Sadly, I get my same core dump. It seems to be a bit slower though... ;) On to Joe's questions: The compiler is gcc 2.96. Here's a debugger session: [cdwan at alpha platform]$ gdb /tmp/ncbi/ncbi/build/blastall /tmp/core GNU gdb Red Hat Linux (5.1-4) Copyright 2001 Free Software Foundation, Inc. GDB is free software, covered by the GNU General Public License, and you are welcome to change it and/or distribute copies of it under certain conditions. Type "show copying" to see the conditions. There is absolutely no warranty for GDB. Type "show warranty" for details. This GDB was configured as "alpha-redhat-linux"... Core was generated by `/tmp/ncbi/ncbi/build/blastall -d /home/cdwan/pig_seq -i /home/cdwan/seq_2.fsa -'. Program terminated with signal 8, Arithmetic exception. Reading symbols from /lib/libm.so.6.1...done. Loaded symbols for /lib/libm.so.6.1 Reading symbols from /lib/libpthread.so.0...done. warning: Unable to set global thread event mask: generic error [New Thread 1024 (LWP 12287)] Error while reading shared library symbols: Cannot enable thread event reporting for Thread 1024 (LWP 12287): generic error Reading symbols from /lib/libc.so.6.1...done. Loaded symbols for /lib/libc.so.6.1 Reading symbols from /lib/ld-linux.so.2...done. Loaded symbols for /lib/ld-linux.so.2 Reading symbols from /lib/libnss_compat.so.2...done. Loaded symbols for /lib/libnss_compat.so.2 Reading symbols from /lib/libnsl.so.1.1...done. Loaded symbols for /lib/libnsl.so.1.1 reading register pc (#64): No such process. reading register pc (#64): No such process. (gdb) where reading register pc (#64): No such process. -Chris