Weird network issue after reboot

[OzSpeedway]

Howdy

Was over at my Dad's today and changed the com.apple.boot.plist file. Executed a shutdown and reboot but once the machine came up, the network didn't work.

I have the identical motherboard so I checked everything against mine and it all looks fine - in System Profiler all looks good and the IORegistryExplorer the network is showing up.

However, I cannot get outside of the machine, for example to the router. There seems to be no sane reason why it shouldn't work - firewall is turned off and nothing else is blocking it.

Any suggestions as to where to start looking would be greatly appreciated.

For reference, the mobo is a Gigabyte EP45-UD3L running Snow 10.6.1

Cheers
Bruce