php.ini config issue - testing file upload on 3 different servers

Question

Hi, hope someone can help as I'm not sure what's going on here - I have a live site where I want to allow file uploads of over 2MB. I have set the standard config options in php.ini as follows (running phpinfo() shows these settings fine):

upload_max_filesize 25M 25M
post_max_size   25M 25M
max_input_time  60  60
memory_limit    32M 32M

I also have the same config on a mirror server, where uploads of >2MB also don't work. Both of these servers are CentOS running php 5.1.6, with safe mode on. If I try out the settings above on a local LAMP set up on my laptop, the uploads work fine. So does anyone know if the problem could be a restriction of safe mode or if there are any other settings I need to configure?

Thanks in advance for any pointers.