There can be a lot of reasons why the client can't find the server, but the most common source of problems are networks that, whether by design or by accident, don't support IP multicast quite right. Modern switches often do some clever things using a protocol called IGMP which machines use to subscribe to a multicast "channel"; the switches listen for the subscriptions to decide where to send multicast traffic, but for this to work properly it also needs to be backed up by a router that is configured to emit IGMP queries, otherwise switches time out their internal routing tables and start discarding the multicast traffic (usually after about three minutes, although this is up to the switches).
When it starts up, the server on the console machine subscribes to the multicast group 229.55.150.208 - this looks like an IP address, but it's interpreted differently, and any number of machines can subscribe to receive traffic sent to that group. The clients send out packets on the network to find the server to this group number, and the switches and routers will send the location requests just to the Ghost servers. At least, that's the way it's meant to work.
It's also possible that your router is configured to explicitly block the distribution of multicast traffic, in which case the client falls back to a protocol called WINS (or NetBIOS name service), which is a variant of DNS that works within individual subnets without needing an explicit server (there are various techniques to extend it over multiple subnets). Currently that's the only fallback system we use if the network has problems with multicast traffic.
Since ping uses simple unicast IP packets, it can't tell you much about multicast connectivity (unfortunately, it's something that's flat-out hard to explore - the behaviour of "smart" switches I mentioned above means that simple tests can appear to work fine and then suddenly stop dead).
Being able to support multicast is good if you can, because modern switches can use this to ensure that imaging traffic is efficiently distributed in a way that limits the impact on your network. Unless someone has chosen explicitly to block it, it can be good for the health of your network to ensure that it works properly and that's usually a matter of just turning on a missing option.
So, the first question is, is your network meant to be able to support IP multicast, or not? If so, then there's something going wrong, most likely in the configuration settings which the switches and router need to work together to support this.
If the network is not multicast-capable for some reason, then you need to configure WINS support on your network such that the clients can resolve name registrations made by your server machine.