Apache AH00051 Error

[xplanedotorg]

I'm hoping someone else has seen this error.  We have been seeing these a few hundred a day for a while now and I've tried all kinds of things to reduce with very little luck.  Haven't determine the trigger for it but it is only impacting are largest site running Invision 3.4.7.  All modules are up-to-date and we are using Apache 2.4.10 on an Ubuntu 14.04 server with PHP 5.5.19-1.

Looking through the Internet I've found tons of people seeing these issues but no clear cut answer as to how to diagnose and fix it.  

Usually the error just goes into the error log and has no impact that I can find but every now and then, maybe once a day the server becomes unresponsive (only for this site, I'm running multiple vhosts). and I then have to restart apache in order to clear it.  It will remain in this state indefinitely until I do.  

Has anyone seen this error on their Apache server?  

[Sat Dec 13 13:07:37.703982 2014] [core:notice] [pid 195742] AH00051: child pid 196032 exit signal Segmentation fault (11), possible coredump in /tmp/apache2-gdb-dum

I grabbed a bit more of the log from when it happened last night.  You can see the last two errors followed by the AH00051.  It continues for about 15 minutes till I noticed and restarted the server by issuing a service apache2 restart. I replaced the IPs and full paths with some dots, otherwise, it is unedited.  I really need some help on this one.  Its is causing us a lot of grief and I've spent hours trying to figure it out.  Thanks for the assistance!

[Fri Dec 12 17:52:09.461232 2014] [:error] [pid 119329] [client xxx.xxx.xxx.xxx:50722] PHP Notice:  Constant IPB_THIS_SCRIPT already defined in ......../forums/httpdocs/index.php on line 20, referer: http://www........org/extnewdownloads.html

[Fri Dec 12 17:52:09.495249 2014] [:error] [pid 119241] [client xxx.xxx.xxx.xxx:50720] PHP Notice:  Constant IPB_THIS_SCRIPT already defined in ........./forums/httpdocs/index.php on line 20, referer: http://www........org/extnewdownloads.html

[Fri Dec 12 17:52:09.935894 2014] [core:notice] [pid 119073] AH00051: child pid 119076 exit signal Segmentation fault (11), possible coredump in /tmp/apache2-gdb-dump

[Fri Dec 12 17:52:09.935976 2014] [core:notice] [pid 119073] AH00051: child pid 119082 exit signal Segmentation fault (11), possible coredump in /tmp/apache2-gdb-dump

[Fri Dec 12 17:52:09.936012 2014] [core:notice] [pid 119073] AH00051: child pid 119091 exit signal Segmentation fault (11), possible coredump in /tmp/apache2-gdb-dump

[Fri Dec 12 17:52:09.936041 2014] [core:notice] [pid 119073] AH00051: child pid 119117 exit signal Segmentation fault (11), possible coredump in /tmp/apache2-gdb-dump

[Fri Dec 12 17:52:09.936067 2014] [core:notice] [pid 119073] AH00051: child pid 119121 exit signal Segmentation fault (11), possible coredump in /tmp/apache2-gdb-dump

[Fri Dec 12 17:52:09.936092 2014] [core:notice] [pid 119073] AH00051: child pid 119128 exit signal Segmentation fault (11), possible coredump in /tmp/apache2-gdb-dump

[Fri Dec 12 17:52:09.936143 2014] [core:notice] [pid 119073] AH00051: child pid 119212 exit signal Segmentation fault (11), possible coredump in /tmp/apache2-gdb-dump

[Fri Dec 12 17:52:09.936180 2014] [core:notice] [pid 119073] AH00051: child pid 119241 exit signal Segmentation fault (11), possible coredump in /tmp/apache2-gdb-dump

[Fri Dec 12 17:52:09.936217 2014] [core:notice] [pid 119073] AH00051: child pid 119253 exit signal Segmentation fault (11), possible coredump in /tmp/apache2-gdb-dump

[Fri Dec 12 17:52:09.936256 2014] [core:notice] [pid 119073] AH00051: child pid 119288 exit signal Segmentation fault (11), possible coredump in /tmp/apache2-gdb-dump

[Fri Dec 12 17:52:09.936301 2014] [core:notice] [pid 119073] AH00051: child pid 119290 exit signal Segmentation fault (11), possible coredump in /tmp/apache2-gdb-dump

[Fri Dec 12 17:52:09.936342 2014] [core:notice] [pid 119073] AH00051: child pid 119329 exit signal Segmentation fault (11), possible coredump in /tmp/apache2-gdb-dump

[Fri Dec 12 17:52:09.936391 2014] [core:notice] [pid 119073] AH00051: child pid 119364 exit signal Segmentation fault (11), possible coredump in /tmp/apache2-gdb-dump

[Fri Dec 12 17:52:10.939808 2014] [core:notice] [pid 119073] AH00051: child pid 119078 exit signal Segmentation fault (11), possible coredump in /tmp/apache2-gdb-dump

[Fri Dec 12 17:52:10.939869 2014] [core:notice] [pid 119073] AH00051: child pid 119119 exit signal Segmentation fault (11), possible coredump in /tmp/apache2-gdb-dump

[Fri Dec 12 17:52:10.939885 2014] [core:notice] [pid 119073] AH00051: child pid 119124 exit signal Segmentation fault (11), possible coredump in /tmp/apache2-gdb-dump

[Fri Dec 12 17:52:10.939909 2014] [core:notice] [pid 119073] AH00051: child pid 119145 exit signal Segmentation fault (11), possible coredump in /tmp/apache2-gdb-dump

[Fri Dec 12 17:52:10.939926 2014] [core:notice] [pid 119073] AH00051: child pid 119155 exit signal Segmentation fault (11), possible coredump in /tmp/apache2-gdb-dump