Causes Of Failed Large Uploads Via Form

I just moved to a new, dedicated server this week. My vbulletin forum users typically upload mp3 files under 10MB. At the moment, I can't seem to get anything above 6MB to work.

In vBulletin land, they recommend changing these in php.ini:
upload_max_filesize - Largest size of a file to accept.
post_max_size - Must be larger than upload_max_filesize.
memory_limit - Should be larger than post_max_size.
max_execution_time
max_input_time

I've cranked all of those up and restarted Apache.

I'm still having the same problems. The little window with the form turns white after what appears maybe 5 minutes, but I haven't timed it.

They also mentioned changing the LimitRequestBody in Apache. I appear to be screwing that part up so I created a thread in the Apache forum specificallya about that.
[url]

So I wanted to ask if there were any other possibilities that you guys could think of that would inhibit the file size up uploads via a form.

I'm running httpd-2.2.8 and php-5.2.6. It needs to be said that this forum is config is mostly right out of the box. $_SESSION wouldn't work in php until I changed the directory for it yesterday. So there may be a very basic config setting that I missed.

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I decided to check my error logs.

PHP Fatal error: Allowed memory size of 33554432 bytes exhausted (tried to allocate 9852343 bytes)

I'm confused. I have an allowed memory of 30MB (give or take). So why does a 10MB file "exhaust" it?