no signal after a minute ir so

hi guru's
if you can't help, I understand. I have a computer I know nothing about. I turn it on, it goes to the screen where I can choose a user. I chose administrator and before my personal settings are finished loading, I get a no signal error.

 

Something could be sick in there.
Have you tried Safe Mode?
Check all connections inside and out to make sure everything's properly seated and connected? Blow out any dust.
Try it with just one RAM stick, and try different sticks in different slots.
Disconnect all unnecessary peripherals - DVD/CD, Internet, speakers...
Try booting with a Linux disk.
Are the fans running? - probably not on long enough to have an overheating problem though.