ACER Windows 7 Mini Laptop Failure?

My laptop acer window 7 mini laptop use to hang. Sometimes it hangs while booting,sometimes when it has finish booting,sometimes while am working or trying to save a document.Whenever it does that i will short down through the start up button then switch it on again. The system will then give options of choosing repair my computer automatically or start window normal. Most often it still hangs even while i chose repair automatically,the same goes to start window normal. Sometimes it will start working again and then stop any time it chooses.