kalale, I'd second that of KiLLaBeE's sequential testing. This way you'll pinpoint the problem.
I'm guessing this "no-ip" application is some kind of dynamic DNS program that updates your DNS name on root servers with your dynamic IP address from your ISP...am I right?
Yup, absolutely KiLLaBeE, Except that (as far as I know) it does not need to update the root servers. It updates their own DNS servers with the correct IP. In a way it's similar to DynDNS.
