Internet crashes when using IDM

Hello,
Never had this problem before but just recently bought a new laptop with Vista and when i start downloading with IDM(internet download manager) my internet stops working. Not only on my pc but even my xbox wont connect to xbox live until i reset my modem. it works fine with a cable connection but not wifi, i have tried turning off firewalls, i also reset and reconfigured my router, it work fine for a few days then return again. also i am using norton 360 if that helps.
any help appreciated, thanks