At first, it opens just fine until the page where I need to key in my password open. After I press enter, it will take at least 10 minutes to open to the main screen. And sometimes my laptop fan works and sometimes doesn’t so it gets overheated. (But it doesn't turn off by itself) What's wrong with my laptop [Dell]?
Disable as many as possible of startup programs and unnecessary services and see if its helps, and once you enter your password try to run Task Manager and see if there is anything eating a lot of your resources
Make sure your PC is clean from viruses and malwares
If you are on windows 8.1 (maybe in newer versions too, not sure about this) try going to Control Panel - Hardware and Sound - Power Options - On the left click on "Choose what the power buttons do" - Click on "Change settings that are currently unavailable" - Scroll down and if you find "Turn on fast startup" unchecked, check it.