Is it a DSL or cable modem? If so, is it plugged in the Ehternet port or in the USB port? If it is in the USB port, you should probably install the modem driver. Also, if it is DSL, is your wiring correct? Did you install the filters on all phone plugs EXCEPT between the DSL modem and the wall plug? Maybe the firmware in the modem got buggy, so maybe you should flash the firmware. It can be a lot of things... give us a little more details, like type of Internet connection (DSL, Cable, 56k, etc) make and model of modem, drivers, etc, etc.