The other day, my Mom had been using her computer, when she left it for a minute. On her return, the system was frozen, so she shut it down completely and turned it back on. When she turned it back on she got the No Signal message. When I hooked up her tower to my system I got the No Signal message as well. I'm sure you need far more information to help me figure out what's wrong, but being a complete computer illiterate, I've no idea even what information to supply. Any assistance would be greatly appreciated.