all in one

hi,

all in one- product #   Qu127AA#ABA, MODEL #120-1024, HP OMNI 120, SERIAL4CS1430    I AM HAVING START UP PROBLEMS,   AFTER ON AND PUT IN PASSWORD COMPUTER GOES BLACK SCREEN,    I CAN GO ON SAFE MODE  .

WHAT CAN I DO TO RESOLVE THIS PROBLEM?  THANK YOU KENNETH ORTIZ