HP Pavilion 10-e010nr OS/Software :: Won't Get Past Screen With Logo And Circle Of Dots

I recently bought a HP Pavilion computer (HP Pavilion 10: 10-e010nr). This was my first experience with Windows 9.1, but everything seemed to be going OK. Then, yesterday  when I had to enter my password again, the computer began running very slowly and then seemed to lock-up; it wouldn't do anything. I held the "on button" until the computer shut down and then restarted it. When it restarted, it didn't get past the initial screen that shows "HP" within a blue circle and the small circle of small, white dots shows that it's working but nothing ever happens. I tried this numerous times, but the same thing happens.