Over the past 2 days one of our clients has had issues with 2 of their 2.5.2 esx server.  The first issue was easily resolved by the following command
/etc/init.d/httpd.vmware restart

However on the 2nd box after issueing that command nothing happened.  So I rebooted the esx machine via ssh(putty).  After that did not fix things I did a df -h command and I saw that the / partion was 100% full   there in was my problem.  Probably you have /var/log/ is full of old log messages.  do a rm -rf of the specific log files that have a .1.2.3.4.5.6 on the end.  then you are good to go.