Ubuntu Networking :: My Internet Connection Has A Long Delay

My problem is that every time I use the Ethernet connection (I don't have wireless card) there is a delay of around 30s, even though my download speed is not affected at all once the connection is "established" , no matter what application I use (Synaptic, ssh, firefox, google chrome,wget, update manager, etc.). A weird thing is that my ethernet connection always appears as active.

I'm sure I'm not the only one who has experienced this issue, since I've read the same problem on other forums, but no one has come up with a solution. I hope that there will be a solution at last by this time.
I've been around with this problem for about 1 month, I've tried all sorts of tweaks that involve disabling ipv6 and nothing happens. I don't really know what triggered off this issue because it all started all of a sudden and I don't remember having installed any important update by the time this happened (I did a clean installation of Ubuntu 10.04 32bits on the release date).