I have an older HP Pavilion model running Windows 98. If I turn the machine off, or if it crashes (as it does frequently these days) it will not restart unless I leave it off from 15-30 minutes. If I try to restart after a shorter "off" period I get, often, a funny sound through the speakers, and always a message on the screen saying "Please Check Signal." Then after another 15-30 minutes of "rest" it will fire up. I have a newish power supply, as the old one failed a few months ago. Any help will be greatly appreciated.