Doubtful.
Usually, these sorts of bans that mention trojans are actually triggered by others who use the same host as you do. Depending on the number of infected computers connecting through a given host, a network may completely g-line that host (and since it's a g-line instead of a k-line, I'm betting that is the case). This can happen a LOT if you use a college network, for example. You may be clean, but you're banned because someone else had a virus or trojan.
Sometimes, certain servers on a network will still let you connect. Even if they don't, these bans can often be set for only 24-48 hours. The best thing you could do would be to contact the network. The website they gave you should have contact information, if the message sent to you when connecting does not.
A word of warning... be wary of clicking any links from IRC, especially ones that say you are infected with something. If you get it when attempting to connect to the server (before you actually connect), then it should be safe. Once you are online, those messages are usually linking you to the virus itself so that you will become infected. This also goes for almost all porn links.
