Ok, my IMac that I had a while now has this problem where everytime I turn on the computer, it's about to start up the desktop and show all my things. But then it seems that the whole screen ends up turning light blue then happens the same thing where it's about to load my desktop again. I can't even use my computer anymore. I was also having a problem with the Graphics Card before this happen, there would be lines and messed up texts. Please tell me how to fix this problem!