My mac is rebooting everytime I login
After reading a bit through the internet I found the 'safe mode', there I deleted some random files from the desktop, and changed the dock settings so it is always visible (I don't think these had any effect). Then I restarted and made sure the little checkbox next to '' is empty (probably this made the effect). When the computer started I could log in, but it is still weird, the desktop background image disappears and comes back, no dock, ... see my followup question.

The next time I logged in I moved all the apps to the trash, just in case.