my system:  
kjetil@familien:~/git/incanter$ lsb_release -rd
Description:	Ubuntu maverick (development branch)
Release:	10.10

my gcc version: (standard version from ubuntu Maverick):

kjetil@familien:~/git/incanter$ gcc --version
gcc (Ubuntu/Linaro 4.4.4-14ubuntu3) 4.4.5
Copyright (C) 2010 Free Software Foundation, Inc.
This is free software; see the source for copying conditions.  There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.


I was  compiling gcc version 4.5.1 from source, using the tarball downloaded
from the gnu site:        gcc-4.5.1.tar.gz

I was building this with the incantation:

kjetil@familien:~/gcc/gcc-4.5.1-objdir$ ../gcc-4.5.1/configure --program-suffix=-4.5.1 

kjetil@familien:~/gcc/gcc-4.5.1-objdir$ make profiledbootstrap

resulting (after a long time) in the segfault:

.
.
.
libtool: compile:  /home/kjetil/gcc/gcc-4.5.1-objdir/./gcc/xgcc -shared-libgcc -B/home/kjetil/gcc/gcc-4.5.1-objdir/./gcc -nostdinc++ -L/home/kjetil/gcc/gcc-4.5.1-objdir/i686-pc-linux-gnu/libstdc++-v3/src -L/home/kjetil/gcc/gcc-4.5.1-objdir/i686-pc-linux-gnu/libstdc++-v3/src/.libs -B/usr/local/i686-pc-linux-gnu/bin/ -B/usr/local/i686-pc-linux-gnu/lib/ -isystem /usr/local/i686-pc-linux-gnu/include -isystem /usr/local/i686-pc-linux-gnu/sys-include -I/home/kjetil/gcc/gcc-4.5.1-objdir/i686-pc-linux-gnu/libstdc++-v3/include/i686-pc-linux-gnu -I/home/kjetil/gcc/gcc-4.5.1-objdir/i686-pc-linux-gnu/libstdc++-v3/include -I/home/kjetil/gcc/gcc-4.5.1/libstdc++-v3/libsupc++ -fno-implicit-templates -Wall -Wextra -Wwrite-strings -Wcast-qual -fdiagnostics-show-location=once -ffunction-sections -fdata-sections -g -O2 -D_GNU_SOURCE -c ../../../../gcc-4.5.1/libstdc++-v3/src/pool_allocator.cc  -fPIC -DPIC -o .libs/pool_allocator.o
In file included from ../../../../gcc-4.5.1/libstdc++-v3/src/pool_allocator.cc:31:0:
/home/kjetil/gcc/gcc-4.5.1-objdir/i686-pc-linux-gnu/libstdc++-v3/include/ext/pool_allocator.h: In constructor ‘__gnu_cxx::__pool_alloc<_Tp>::__pool_alloc() [with _Tp = char]’:
../../../../gcc-4.5.1/libstdc++-v3/src/pool_allocator.cc:171:18:   instantiated from here
/home/kjetil/gcc/gcc-4.5.1-objdir/i686-pc-linux-gnu/libstdc++-v3/include/ext/pool_allocator.h:140:30: internal compiler error: Segmentation fault
Please submit a full bug report,