PHP Fatal error: Out of memory - HELP

[PPNSteve]

WHM 11.15.0 cPanel 11.17.0-R19434
REDHAT Enterprise 4 i686 on standard - WHM X v3.1.0 with 2GB RAM

just rebuilt apache 2.2.8, with php 5.2.5.. trying to solve a random apache crash issue.. now it's worse with this error being generated almost all the time:

PHP Fatal error: Out of memory (allocated 786432) (tried to allocate 1245184 bytes) etc.

the byte values may change some but never even come close to the 128MB limits we have set in php.ini

any suggestions? this is driving both me and my DC techs nuts trying to find the cause..

[jayh38]

What application are you running to get that error? is the new allocated memory showing properly in phpinfo(): ???

[PPNSteve]

we increased it to 192MB to see if that helps any..

We're running various php scripts provided by vBulletin (forums)

max_execution_time 60 60
max_input_nesting_level 64 64
max_input_time 60 60
memory_limit 192M 192M

anytime the server gets slightly busy it starts happening.. this is a fresh install of RHES4 as well as the forum files..

[troxalias]

Maybe your problem is related to http://bugs.php.net/bug.php?id=39438 .

[PPNSteve]

hmm.. not quite.. but I can tell you, its related to PHP, apache and mysql's interaction as well as whatever else the server is doing in the background i.e. cPanel updates, running logs, etc.

A google search returns 1000's of recent related issues so I'm not the only one out there seeing this problem. My DC techs are stumped, the vBulletin staff is blaming the server setup, and my techs are blaming vB.. what a mess.

also of note, this NEVER happened before the php upgrade to 5.2.x / apache 2.2.x setup.. same box although a newly installed RHE4, same scripts (less in fact since we didn't move some other sites over on the new OS install)
mem has been tested, OK

leaves pretty much either settings SOMEWHERE or PHP itself (memory leaks?)

all we need is a solution now.