Asus P5GZ-MX cant get into safe mode

My pc was froze up nothing would open today and i pulled up the process's running and saw something that didn't look right thinking it could be some Trojan of some sort so i end task and comp shuts down. now it will not restart. i get the post and bios and i can get into cmos..but i get a blinking _ and then black screen..nothing. onboard or video card nothing. i push f8 and get to choose what device to boot from ..i tried pushing f8 sooner and later reading that asus made it the same button yeah go asus..if i do get f8 at the right time it just goes black before bios and no post or cmos....something is not right. hope it is not my harddrive. anyone have any ideas?? should complete be shut out of windows for closing something..it tells you that you are not aloud to close certain things if it is needed to run windows. it blocks you from doing so. i need help any ideas guys???