Dyndns, Lookup, Ping and Traceroute... weird!

Dear community,

I am using dyndns to get a domain name, in order to access my mac when out from home.

Everything worked fine for months up to a couple of days ago...

Now, when I try to access my Mac at home when I am away, ie from work, I get the error:

Firefox can't establish a connection to the server at xxx.dyndns.org:xxx.

I digged in the utilities folder, fired up Network Utility.

Using LOOKUP and serching for my host (<hostname>.dyndns.org>), I get the error message:

Trying "<hostname>.dyndns.org"

;; connection timed out; no servers could be reached

Using PING, and entering the SAME hostname, it DOES work, and I get the numeric IP address assigned by my ISP associated with dyndns.

The same using TRACEROUTE: it goes through many steps, but then it finds my mac, and with the right numeric IP address.

I tried to reset the DNS cache, to change the DNS server, to reboot, to use a different browser... No way...

In network utility, Ping and Traceroute can find the numeric IP addressed assigned to my mac by my ISP and associated with dyndns, but Lookup doesn't...

By the way, I can access remotely my home webcams through the application "IP camera viewer 2" and configured to use the dyndns host name...

If I type in the numeric IP address rather than <hostname>.dyndns.org, I get the same error in firefox...

In summary:

the right, temporary IP address assigned by my ISP is correctly registered on dydndns.org

traceroute and ping can find this IP address

i can access remotely my webcams through an application...

Lookup DOES NOT find the host

firefox or safary DO NOT find the host...

I am relly lost.

whazzup?

Does anybody has a suggestion? Thanks a lot in advance!