Laptop turns on, and loads but it starts over

Hello,

My laptop is an Acer Aspire One. I would turn on my computer and it would go to this black background where it says "Start Windows Normally" and i would pick that. then it would go to the Windows loading thing but then it would start all over and go to the black background again and i would choose the "Start Windows Normally". How do i get to my main deskstop and have this thing to stop? please please help!!