I can't connect Nor can anybody else

[Talon]

It was alworking fine for me, I had Joomla CMS installed and I had my site up for 2 days. That is until I installed Invasion Power board. Now NOBODY can connect to my site not even me (except for in local host) I have turned off everything, and turned it back on, turned off my computer and waited and I even checked my router to see if mybe the settings reset themselves. I can still connect to the internet from the server (I am writting this message from the server right now) but I can't connect on the URL that I recived from DYNDNS.org (hcp.shacknet.nu/eng) so now I am stuck, any suggestions? (Note I have heard that Joomla CMS was vulnerable to a DOS attack, are these signs of that?)