Whenever the connect automatically when needed option is checked in PPP options my computer conects to the internet every few minutes for no apparent reason, even when there are no applications open and it has been freshly restarted. Does anyone know what causes this and how to fix it other than by just deselecting this option?

Ed, I do believe.... that it can't be stopped except by unticking "Connect automatically when needed". The reason might be that OS X appears to rely so very heavily upon a constant connection to the internet - Sherlock uses the internet - all the Help files require internet access - Software Updates regularly checks the Apple Site for updates - even the clock is checking its internal time against the Network Server Time. However - be this as it may - try this: Go to the blue Apple -->> scroll down to "System Preferences..." - and in System Preferences, choose "Sharing" - under the heading "Internet & Network". In Sharing - under "Services" - untick every box - (if you're on a local network with other Macs around you then "Personel File Sharing" can be ticked - or if your networking with a local PC - then "Windows File Sharing" can be ticked also) - but apart from these two - untick all the rest. If this fails - try activating the next tab "Firewall". tell us how you went cheers clockwork

No luck Thanks anyway any other ideas anyone?