If you find the error messages in /etc/httpd/logs/error_log as follows :-
[Tue Mar 28 04:29:42 2006] [notice] child pid 24546 exit signal File size
limit exceeded (25)
This means that you have a log file that is greater than 2GB in size.
To fix this run the following :
du -sh * | grep [0-9]G
This should show you the file that is causing issues e.g. example.com.log.
To reset it, but loosing the webstats run
Do not use just an Apache restart but a full stop/start to make sure it closes all its old files.