Network Connection crashing My computer

Hi I hope someone can help me here...

I have an HP laptop, about three months old with Vista home premium installed. Was working fine until about four days ago . Now whenever I am connected to a modem either wirelessly or via ethernet the computer freezes after about a minute and I have to unplug and reboot. This happens regardless of whether I am browsing the net or not. When I disconnect the modem the computer runs without a problem. I have tried the computer in different locations with different modems and the problem is still there.

I have run Reg cure that didn't make any difference. Also ran Trojan remover which found no problems.

I am wondering if anyone has any ideas or has experienced the same thing. I am guessing it may be a vista problem but havn't really got a clue what to try next. Any help would be much appreciated!!