Hi there Pcjerry,

I have ofetn seen a faulty modem cause a pc not to boot up (mine included). This is usually caused by some sort of power surge coming down the phone line, which blows the modem. Unfortunately the only cure I know of is to replace the modem. Dial up modems are not all that expensive at the moment so you should be able to fnd one cheaply (try to get one with the driver cd, if not post the make and model and we'll try to find them for you)
All the best.