safe mode goes to blank screen

hi , i need some help if any one knows what to do please help
anyways im using windows xp , got a trojen virus , downloaded avg to clean it , was asked to force remove it , the pc shut down , and then when it restarted asked me to start in safe mode , when i hit safe mode the screen goes blank,except the mouse pointer, tried all the other options when booting and pressing F8 , it still wont work , can anyone help with this pleeeaaasse....

thanks in advance

Arthur