Same probleme here, using php-4.4.1 and httpd-2.0.55 (both built from source). It may also be a HTTPd problem.

Ok, downgrading to 4.4.0 fixed this issue.

This works fine in 4.4.2-dev and 5.1.0RC5 

I am not sure why this was closed.  Downgrading is not a solution to this issue.

Has anyone fixed this?

Thanks.

Not enough information was provided for us to be able
to handle this bug. Please re-read the instructions at
http://bugs.php.net/how-to-report.php

If you can provide more information, feel free to add it
to this bug and change the status back to "Open".

Thank you for your interest in PHP.

OK. This is broken for us, too.
Platform details: 
* Apache 2 built from source[0].
* php 4.4.1 built from source[1]

In httpd.conf for a virtual host:
* ErrorDocument 404 /errordoc.php

What I did?
* caused a 404 by going to non-existent page
What I expected?
* errordoc.php to be served
What actually happened?
* "Error reading from socket" -- nothing is served.

This used to server errordoc.php prior to the upgrade to 4.4.1.

[0]
export CFLAGS="-DOPENSSL_NO_KRB5=1"
./configure --prefix=/usr/local/apache2/ --enable-so --enable-mods-shared=all --enable-auth-dbm --enable-proxy --enable-proxy-http --enable-ssl --enable-rewrite --with-ldap --enable-ldap --enable-auth-ldap

[1]
./configure  --with-mysql --with-openssl  --with-dom --with-zlib --with-xml --with-apxs2=/usr/local/apache2/bin/apxs --prefix=/usr/local/php-apache2 --with-pgsql --with-ldap --with-mcrypt --with-gd --with-jpeg-dir=/usr

apache 2.0.55(source), php 4.4.1(source), FC2.
exactly the same problem as described above. apache only segfaults when errordocument page is set to a file. tried php and html extensions. when errordocument is set to some text message: 
i.e.  ErrorDocument 403 "page doesn't exist"
all is fine.
related strace output:

[pid 12688] getsockname(9, {sa_family=AF_INET, sin_port=htons(80), sin_addr=inet_addr("local_ip")}, [16]) = 0
[pid 12688] fcntl64(9, F_GETFL)         = 0x2 (flags O_RDWR)
[pid 12688] fcntl64(9, F_SETFL, O_RDWR|O_NONBLOCK) = 0
[pid 12688] read(9, "GET /asdfdasfd HTTP/1.1\r\nAccept:"..., 8000) = 416
[pid 12688] gettimeofday({1132605779, 447411}, NULL) = 0
[pid 12688] stat64("path_to_nonexistent_file", 0xbff19abc) = -1 ENOENT (No such file or directory)
[pid 12688] lstat64("/www", {st_mode=S_IFDIR|0755, st_size=440, ...}) = 0
[pid 12688] lstat64("path_to_dir_three_levels_up_from_nonexistent_file", {st_mode=S_IFDIR|0755, st_size=136, ...}) = 0
[pid 12688] lstat64("path_to_dir_two_levels_up_from_nonexistent_file", {st_mode=S_IFDIR|0755, st_size=72, ...}) = 0
[pid 12688] lstat64("path_to_dir_where_nonexistent_file_is", {st_mode=S_IFDIR|0755, st_size=176, ...}) = 0
[pid 12688] lstat64("path_to_nonexistent_file", 0xbff19a9c) = -1 ENOENT (No such file or directory)
[pid 12688] gettimeofday({1132605779, 452037}, NULL) = 0
[pid 12688] write(7, "[Mon Nov 21 12:42:59 2005] [erro"..., 135) = 135
[pid 12688] stat64("path_to_404.html", {st_mode=S_IFREG|0644, st_size=1572, ...}) = 0
[pid 12688] lstat64("path_to_404.html", {st_mode=S_IFREG|0644, st_size=1572, ...}) = 0
[pid 12688] --- SIGSEGV (Segmentation fault) @ 0 (0) ---
[pid 12688] chdir("/www")               = 0
[pid 12688] rt_sigaction(SIGSEGV, {SIG_DFL}, {SIG_DFL}, 8) = 0
[pid 12688] kill(12688, SIGSEGV)        = 0
[pid 12688] sigreturn()                 = ? (mask now [])
[pid 12688] --- SIGSEGV (Segmentation fault) @ 0 (0) ---
Process 12688 detached

No feedback was provided for this bug for over a week, so it is
being suspended automatically. If you are able to provide the
information that was originally requested, please do so and change
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