losing internet connection

I am losing my internet connection some thirty seconds after logging in. How can I go about analyzing the problem? I have a wired connection to the internet.

It can't be a hardware problem since I have no problem in windows XP.

I use kubuntu hardy, I have installed ubuntu-desktop and I see the same problem when I log into an ubuntu session (I also see some pesky message about HAL in ubuntu).

do you dial to connect to the internet?

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