log on xp problem

hi when ever i start my computer up i can only get as far as the log on screen, i have two options for log in admin and guest. i have tried both names but get the same problem, it starts saying loading personal settings.... then it says playing logoff sound.....then saving your settings and that's all it does just bringing me back to same options, i have repeated several times rebooted alot also and same in safe mode nothing working i also tried ctrl alt & del from the log on screen and it ask for windows username and password which i have also tried but same problem again :(

could anyone pleaseeeee help?!?:(