Out of Memory Issue

[ClaraLeigh]

Hey,

I am having a very odd error that has had me scratching my head for days.
Basically, I installed composer on our server running CENTOS 5.11 x86_64
Composer works perfectly fine, under the root user.
It does not however run under a normal, non-root user or even under a sudoer.

Any possible command I try will return nothing.
Including:

• composer (remembering that its installed globally and working for root)
• curl -sS https://getcomposer.org/installer | php
• php -r "readfile('https://getcomposer.org/installer');" | php
• curl -sS https://getcomposer.org/installer | php -- --check

I have also downloaded the composer install file (https://getcomposer.org/installer) and tried to run it by using :
php -dmemory_limit=-1 composer-file
(I have also increased the memory limit in php.ini and inside the composer install file manually to 1G)

Permissions for the global file:
-rwxr-xr-x 1 root root 1074598 Mar 11 16:26 /usr/local/bin/composer

I have also tried making the user I am testing the owner/group and also giving the file 0777 permissions.

If I look in the apache error log, I see the following error message:
[23-Mar-2015 12:10:42 Australia/Brisbane] PHP Fatal error: Out of memory (allocated 262144) (tried to allocate 1074630 bytes) in Unknown on line 0

Also, when trying to run the command using sudo (eg: sudo composer), I get a 500 internal server error appear in the console when normally nothing appears when running a command.

Also, when downloading and running the install file locally, I found that it runs out of memory the line after "return <<<'CACERT'" inside this function:
public static function getPackagedCaFile()

Any help or possible ideas on what could be causing this would me appreciated.

Thank you :)