Different computer problems every time i start it seems?

Ok the first thing that went wrong was that there was a blinking white cursor on the screen before it loads the operating system. Well eventually i got that working, i scanned for viruses updated windows. And then the next time the monitor doesnt work. keep in mind i never moved anything so the monitor that worked before isnt working now. Do you think its a video problem or what. Also note the num/caps/scroll lock lights do not turn on. and the mouse light doesnt turn on. the fans on spinning and the hard drive is spining and the cdrom drive opens. I also know its not the monitor because it will say no signal on the monitor. But then sometimes when i turn the PC on i see the display just like normal and then it goes to the blinking white cursor again.this is a desktop. please help.