Whenever you feel boring with Windows and want something different (for example Ubuntu Linux), you better think twice!
If You don’t have them both, The Windows Installation disc and the Ubuntu installation disc, then You’re screwed!

I took my laptop, inserted the Ubuntu 11.04 installation disc, rebooted my computer, and decided to dualboot it with Windows 7, which was installed earlier, as my primary and only Operating System.
My first and current laptop (the HP 625) was not designed for Ubuntu, so the installation failed many times.
I entered a code which temporarily fixed the installation bug. I installed Ubuntu several times, but the last installation screwed everything up! In the next restart, I couldn’t access Ubuntu anymore! Couldn’t access the Ubuntu Installation disc, couldn’t install Windows because I chose Ext4 file format (the default Ubuntu format), which was an unknown format for Windows. So, I wanted to install Windows XP in order to download a program called EASEUS Partition Master to convert the Ext4 file format back to NTFS, and then install Windows 7! How would I be able to install Windows XP? –There was a small partition (1.7GB) which was reserved for “HP Tools”. I couldn’t install Vista or 7 because the partition was not big enough to fit one of them, but it was big enough to fit Windows XP. So, I took my Windows XP installation disc, inserted it on my laptop’s drive and tried to format, but It showed me a Blue Screen. I tried three times, but it didn’t work. I was in panic! What the hell is going to happen to my new laptop? It hasn’t been even two weeks since I got it, and now it was ruined!
So, I did a research on many forums until I found a solution. Actually, I knew the solution, but I was so worried that I forgot what to do. So, the solution was:
After Windows couldn’t format an “Ext4” file format to NTFS, I deleted the whole partition, and created a new one. This time, in NTFS. Thank God it worked and now I am feeling much better.
This was my mistake for trying to install Ubuntu on my Laptop. Maybe Ext3 might work, but to be honest, what is Linux useful for? Security? Security is not the main thing of a computer. As the French cook (my tutor) said: “It’s not us who should fulfill the computer’s needs. It’s the computer which should fulfill OUR needs!”