2MB upload limit problem - all usual solutions tried

Hi all,
I am running a virtual learning environment called Moodle which is
based around PHP and MySQL. This involves users uploading files.
However, I cannot raise the 2MB limit. I'm running Apache 2.0.40 and
PHP 4.2.2-17.

/etc/php.ini contains
"upload_max_filesize 32M
post_max_size 32M"

/etc/httpd/conf/httpd.conf contains "LimitRequestBody 33554432" - does
it matter where this is in the file? It has been suggested that this
should be set to zero, but when I do, I get an error saying it should
be a non-negative integer.

I have no .htaccess file overriding settings. There's nothing
overriding anything in /etc/php.d/

Even with the above, the 2MB limit will not change (and I have
restarted Apache). I have tried changing other parameters in php.ini
and it's definitely the file the system's looking at.

I'm trying everything I can, but I'm on a steep learning curve. Any
help to rasie this 2MB limitwould be *much* appreciated

Regards
Richard Williamson