It just says "Limewire is currently connecting to the network" when I do a search. The internet is working fine otherwise. What could be the problem?

Sounds like you are not connected to the network. One green bar only means you are not connected.

Check these suggestions: If LW Will Not Connect (click on the blue link)

Make sure you added LimeWire (LW) to your windows firewall exceptions.

I've tried a lot of these suggestions and nothing has happened.
The thing is, when I start Limewire, the "Limewire has detected a firewall" icon comes up in the bottom corner of the screen even when I turn my windows firewall off. I don't have any other firewall running as far as I know. My PC was attacked by a trojan a couple of weeks ago, and I'm convinced there is a connection, even though I effectively removed it.

Can anyone tell me a way on Windows XP to check what the firewall could be on my system that Limewire is detecting? Because it definitely isn't Windows Firewall.

Deleting the Gnutella.exe file worked for me and I am running Vista.

Most likely your modem or router. But since you didn't tell us about that. I will use my esp & pretend I know exactly which brand & model you are using, & pretend the best advice is to port forward the device.