I have a Redhat Enterprise Linux 3 server and my kernel is 2.4.21-37.ELsmp

I have a 4GB file that I want to offer on my site as a direct link (no it's not a copyrighted dvd iso or anything questionable), but I keep getting a 403 error. I know the URL is correct, because I went into Cpanel's file manager and copied the path from there and it still didnt' work.

df -hT says that I have ext3. Pure-ftpd doesn't even see the file but proftpd does. I'd allow my users to download it using ftp, but I was told that I shouldn't use proftpd because pure-ftpd is better and more safe.

What am I missing?

Thanks.