runouw.com

See, this is why you go with a completely free option like ChatZilla. It gives you a lot more control than Mibbit, and is also full of open source goodness. Go Firefox!

I don't shut down my computer. Ever.
So I only get that message every once in a while when I actually need to shut it down.
I prefer Google Chrome and mIRC
it has cool customization like the one Foru posted