I swaped a crappy old PIII system with a neigbour for an iMAC. and I need some help getting it on my home network.

It finds the network ok and works on the internet straight away.
but after a shutdown or restart it just boots to a flashing Earth (globe) icon and sits there flashing at me forever and ever and ever.

Then the icon changes to a small folder icon with a face and a question mark alternating flashing.
I think the face icon is the finder (what ever that is).

if I pull the cat5 out of the bastard it talks to me and boots up.
WTF is going on ?????????

Ok I found out what was happening, some how the startup option got set to network boot, I changed it to OSX. and it boots good.

But I get this error msg every boot up.
"You do not have an active modem, airport or PPPoE network port config "
Quit________Use VPN ________Add

I click quit and every thing is fine, i can browse the web etc.
But how do I kill this error MSG ?