That's happening to me as well, I've had to stop trying to log on because people are getting mad at me for crashing the server. :(

I'll fix that right away

You're gonna have to go to spamhaus.org to get your IP delisted (can't help much with this, I can't remember fully how it's done - it's explained on the site though). I've had to do this on two separate occasions. I also highly recommend that you scan all the computers on your IP address; your IP was 'blacklisted' for a reason and if you don't find and remove the threat your IP might get listed as unsafe again.

Hope you get it sorted out. :)