we have had problems on one of our servers recently.
Pages start to load slowly and ultimately the server becomes overwhelmed.
The only suspicious entry in the logs is
::1 - - [03/May/2007:11:22:21 +0100] "GET / HTTP/1.0" 403 3931 "-" "Apache/2.2.2 (Fedora) (internal dummy connection)"
This starts off happening every few minutes but then continues to happen with increasing regualrity - ultimately every second.