Eircom Broadband self install problem

I'm using eircom self install broadband package. My computer fails to connect to the default gateway. It tries to redirect network settings during set up then fails. I've tried it on another computer and it works without any problems so it's not eircom's hardware.
Could there be a program running that i don't know about e.g firewall. Maybe someting is messing with my network card.
I need to find a solution. Anyone?

Maybe the network settings are statically assigned in the first (failing) case and dynamic in the second (working) case?

Are you using the USB connection? If so I had problems with it too and was adviced to switch to the ethernet one by someone in work. I tried it and it worked.