Apache Won't Terminate Connections, We're About To Give Up!

I've got an older "Super Server P4" series server @ ThePlanet - it's been a great box for years. We recently upgraded php4 to php5 and did a mysql upgrade as well. Ever since, randomly, without warning, Apache stops terminating connections, so the max connections fills up, and httpd won't respond. Apache doesn't stop running, it just max's out and stops accepting new connections, so customers assume the server is "down", although email/FTP work fine.

The server never crashes, the loads stay down, but httpd just fills up and won't accept more connections. We can't increase max connections (we actually DECRESED IT), because they'll just keep piling up, never terminating, and then ultimately, it will crash the box.

My admin has worked for nearly 2 weeks trying to figure it out, and Scott (AtomicRocketTurtle) and his team have been evaluating it for about a week - it's happened 3x in 2 days ... last night, httpd quit responding for about 7+ hours and since we didn't have httpd monitoring, we never knew until the office opened this AM and I had two very angry customers. Scott suspects it may be some rogue application that triggers it that didn't affect it prior to the php5/mysql upgrades.

Both Scott and Parm, my admin, have about thrown in the towel and are recommending we retire the server and migrate to a new box.

It's older - much older .. I'm pasting specs below, RHEL3, Plesk 7.5 .. but just wonder, before retiring an old server that was RUNNING GREAT prior to the upgrade, maybe someone has seen this happen before?

If so - PLEASE LET US KNOW before I spend the $$$ on a new box.

Current box's specs:

CPU GenuineIntel, Intel(R) Pentium(R) 4 CPU 2.80GHz
Version psa v7.5.4_build75060118.18 os_RedHat el3
OS Linux 2.4.21-47.0.1.ELsmp
RAM: 1GB, with 2GB swap
apache 1.3.31
bind 9.2.4-20.EL3
coldfusion Component was not installed
coldfusion-support 7.3-2.96.128
courier-imap 3.0.8-rhel3.build75050824.12
drweb 4.32.2-rh7_psa
drweb-qmail 4.32-rhel3.build75050824.12
frontpage 5.0.2.2634
httpd 2.0.46-61.ent
jdk 1.4.2
logrotate 3.7
mailman 2.1.5.1-25.rhel3.7
mod_perl 1.99_09-10.ent
mod_python 3.0.3-5.ent
mysql 4.1.21-2.rhel3.art
perl-Apache-ASP 2.57-rhel3.build75050824.12
php 5.0.4-13.rhel3.art
phpmyadmin 2.5.3
phppgadmin 2.4.2
postgresql 7.3.6-7
postgresql-server 7.3.18-1
proftpd 1.2.9
psa 7.5.4-rhel3.build75050824.12
psa-agent 1.3.2-2_psa7.1
psa-api-rpc 7.5.4-rhel3.build75050930.11
psa-bu 7.5.4-rhel3.build75050926.17
psa-horde 3.0.5-rhel3.build75050824.12
psa-imp 4.0.3-rhel3.build75050824.12
psa-logrotate 3.7-rhel3.build75050824.12
psa-manual-custom-skin-guide 7.5.4-rhel3.build75050824.12
psa-migration-manager 7.5.4-rhel3.build75050930.11
psa-proftpd 1.2.10-rhel3.build75050824.12
psa-qmail 1.03-rhel3.build75050824.12
psa-qmail-rblsmtpd 0.70-rhel3.build75050824.12
psa-spamassassin Component was not installed
psa-tomcat-configurator 7.5.4-rhel3.build75050824.12
psa-turba 2.0.3-rhel3.build75050926.17
qmail 1.03
rblsmtpd 0.70
samba 3.0.9-1.3E.12
spamassassin 3.1.3-1
SSHTerm 0.2.2-rhel3.build75050824.12
stunnel 4.04-4
tomcat 4.1.24-full.2jpp
webalizer 2.01_10-15.ent