To Resolve "exit Signal Bus Error"

We have been dedicated server. In that the following error has been creating Its making severe issue Please help me to resolve this issue.

#grep 'exit signal Bus' error_log

[Wed Jul 16 21:18:45 2008] [notice] child pid 19433 exit signal Bus error (7)
[Wed Jul 16 22:12:56 2008] [notice] child pid 22194 exit signal Bus error (7)
[Wed Jul 16 23:08:53 2008] [notice] child pid 31096 exit signal Bus error (7)
[Wed Jul 16 23:30:29 2008] [notice] child pid 1139 exit signal Bus error (7)
[Thu Jul 17 00:09:58 2008] [notice] child pid 3336 exit signal Bus error (7)
[Thu Jul 17 00:28:03 2008] [notice] child pid 6256 exit signal Bus error (7)
[Thu Jul 17 00:53:55 2008] [notice] child pid 7459 exit signal Bus error (7)

Memory and Hardware test passed (DC people checked). Reload RHEL4 OS with 64 bit.

Server Details:
CPU : Intel(R) Xeon(R) CPU X3210 @ 2.13GHz (4 CPU)
CPU MHz: 2133.413

RAM : 4 GB
Apache : 2.0 (Previously tested with 2.2.9)
PHP : 5.2.5
MySQL : 5.0.1 (Running separate box)

Current Apache Settings:

KeepAlive On
MaxKeepAliveRequests 0
KeepAliveTimeout 5
UseCanonicalName Off
<IfModule prefork.c>
StartServers 5
MinSpareServers 5
MaxSpareServers 10
ServerLimit 2000
MaxClients 2000
MaxRequestsPerChild 0
</IfModule>

Previous Apache Settings:
(Tried with below apache settings on that time also the signal bus error created )

Apache 2.2.9 with eAccelerator compailed.

KeepAlive Off
MaxKeepAliveRequests 50
KeepAliveTimeout 10
UseCanonicalName Off
<IfModule prefork.c>
StartServers 16
MinSpareServers 8
MaxSpareServers 64
ServerLimit 500
MaxClients 500
MaxRequestsPerChild 10000
</IfModule>

Compiled in modules:
core.c
mod_access.c
mod_auth.c
mod_include.c
mod_log_config.c
mod_logio.c
mod_env.c
mod_expires.c
mod_headers.c
mod_unique_id.c
mod_setenvif.c
mod_proxy.c
proxy_connect.c
proxy_ftp.c
proxy_http.c
mod_ssl.c
prefork.c
http_core.c
mod_mime.c
mod_status.c
mod_autoindex.c
mod_asis.c
mod_info.c
mod_suexec.c
mod_cgi.c
mod_negotiation.c
mod_dir.c
mod_imap.c
mod_actions.c
mod_userdir.c
mod_alias.c
mod_rewrite.c
mod_so.c

Apache Server compiled with....
-D APACHE_MPM_DIR="server/mpm/prefork"
-D APR_HAS_SENDFILE
-D APR_HAS_MMAP
-D APR_HAVE_IPV6 (IPv4-mapped addresses enabled)
-D APR_USE_SYSVSEM_SERIALIZE
-D APR_USE_PTHREAD_SERIALIZE
-D SINGLE_LISTEN_UNSERIALIZED_ACCEPT
-D APR_HAS_OTHER_CHILD
-D AP_HAVE_RELIABLE_PIPED_LOGS
-D HTTPD_ROOT="/usr/local/apache"
-D SUEXEC_BIN="/usr/local/apache/bin/suexec"
-D DEFAULT_PIDLOG="logs/httpd.pid"
-D DEFAULT_SCOREBOARD="logs/apache_runtime_status"
-D DEFAULT_LOCKFILE="logs/accept.lock"
-D DEFAULT_ERRORLOG="logs/error_log"
-D AP_TYPES_CONFIG_FILE="conf/mime.types"
-D SERVER_CONFIG_FILE="conf/httpd.conf"

Running single website with drupal based flash arcade website. Per day 2500 visitors and 150 users online normally.

I am almost 3 weeks to resolve this issue.