No mouse and close/maximize button Elementary OS

I've downloaded and installed Elementary OS in my laptop, but something weird is happening with me. I made an USB Flash Drive installation, using UNetbootin. I was able to test it (like a Live-CD) and everything went just fine. So I decided to install it. When I installed it, these bugs started to happen: - The mouse pointer takes ~30 seconds to appear (i'm still able to click things), and when it does, all I see is an "X" on my screen. Perhaps this is the standard mouse pointer, right? - When I try to close or maximize a window, the top bar with these options just doesn't exists. I'm able to drag the window across the screen, but when I double-click (hoping the window will maximize), the system stops working for a while, and then the window crashes. - I've tested Elementary OS before installing. When I click something in the Plank, a small animation starts playing. This doesn't happen in the installed version. There are other things happening, but these are the "main bugs" I can remember now. I tried to do these: - I tried reinstalling the system. Still the same. - I tried to update the system. 100mb of updates, and the bugs didn't go away. - A friend of mine asked me to type "sudo apt-get update" and "sudo-apt get upgrade" in the terminal. Still the same. Since I've always been a Windows user, I don't know why this is happening and neither I know how can I fix this. My laptop config is: Dell Inspiron 14R (5420), Core i7 3612QM 2.10GHz, 8GB RAM, nVidia 630GT 1GB and 1TB storage. Any thoughts?