Sounds to me like you've grown beyond mIRC. You should rewrite this as a web application over HTTP or something. Unless the tasks are IRC related.
That said, you should never be storing your db entirely on the client side. There is your problem. If you want clients to stay in sync, they should be using a centralized database that they all share over the network, they should not be synchronizing their own databases, that's just a headache in any language / implementation.
