Fedora 9 disk full problem

[f f]

It happened today, I was writing some code from Gnome and suddenly I couldn't save.
I installed Fedora on a ide 40gb hdd so it couldn't be full...
du said I have ~30gb in /var/log/httpd. now that was could have been some log file... the problem is that i only installed the system yesterday and just started apache for like 2-3 hours. anyway
i deleted the logs and rebooted

all ok for 1-2 hours, now again disk full, but du says its ok

any ideeas?