Please give us as much information about your computer as possible, Make, Model#, CPU, RAM PSU, Windows version, Video card.
Also when your computer last worked normally, and what happened just before this problem with StartUp, like any Windows Updates, downloading a new program, updating a driver, added a new HDD or DVD burner?
If I understand you correctly, your computer starts to boot up, but gets to the Splash Screen (looks normal?), then stops? Does your computer have a beep code small speaker attached, that beeps once before loading normally? If not, do you have a small 'beep code speaker' that can be attached for diagnostic troubleshooting?
With that information, someone will be able to help you pin down the problem