When I first installed Ubuntu 20 days ago, it started like a purple screen appears with Ubuntu written and loading points and then the login screen. But now when it starts, it is like a purple screen appears and after 2 seconds it goes off and again it appears with Ubuntu written and loading points. Is this normal behavior?

This time when I installed Ubuntu I removed CD from the drive before restarting. I didn't let Ubuntu to first restart and then remove CD. 

Is that behavior related to this happening? This CD thing I've explained [here](https://askubuntu.com/questions/198711/live-cd-crashes-when-removing-it-after-installation). Please explain me.