File size limitation error

I originally posted this as a thread to a related Dreamhost question, however this issue is cropping up on my own RHEL5 server. Apologies for the duplication...

My users are reporting the "Please check with your server administrator about file size limitation..." error. Files in question are of order 100MB

My php settings are as follows and are not being overridden in .htaccess:

max_execution_time = 1200
max_input_time = 1200
post_max_size = 1024M
upload_max_filesize = 1024M

Yet, my users are still reporting the message. Any idea what I might be overlooking?

Is this error being displayed within Omeka, or on an Apache error page? The text "Please check with your server administrator about file size limitation" is nowhere to be found within Omeka's codebase, so my hunch is that your server is limiting the file size -- not Omeka.

Yep, that's the one...

But what else besides my php settings will affect this? (The faq only mentions php settings)

My understanding is that RHEL5 has a version of PHP that's lower than 5.2. Is this correct? Omeka requires PHP 5.2, so I wonder if that is, by chance, contributing to this problem.

True by default, but I am running php 5.2.6...

I have uploaded far bigger files than I am attempting here!