Time Capsule with Wireless & Wired connections

I've been using my Time Capsule as a wireless router (connected to ADSL Nation M3 modem) without problem. At the weekend, my god daughter came to stay and I connected an old (wireless) G4 Imac which we keep in her room to the TC using Ethernet cable.

The problem is, although my other Macs were able to connect wirelessly to the TC, I could not access the internet without first disconnecting the G4! is this normal? If so, is there a work around?

Cheers

have you tried powering everything down first with all the connections intact? If so, look in the network setting on the G4 and look at the configurations. Try releasing the DHCP. You can find that in the advanced button in the network configs under the TCP IP tab. (depending on what OS you are running it may not be that exact route. If not look for something close)