Window xp start up problem

Hello,
my laptop acer has start up problem.when i start window page comes up,then it would not load,so i shut down,again i start,widows apology page to safe mode,recent working conf.etc.if i wait normal start up,sometimes it normally load,other times it does not work.again if i load on safe mode and shut down,then when i start, wlndows load normally.i read a load about this problem in this forum.one problem i cannot use start up cd because my rom is not working.even though laptop is working,it is really annoying to try start again and again.please help.thanks.