I had a complaint from a client that whenever they tried to go to their website (which is hosted externally) they were being redirected to another site. At first I thought that this was just spyware, but then found that it was happening to all the PCs within the network.
I had a look at the A record that had been created for their website in the DNS manager and found that the IP address had changed from what it was for their site. And yes it was set to static.
Other than someone physically going in and editing this record how else could this have changed?