When I start up it goes to a gray screen with a folder with a question mark on it with an alternating face? I tried holding shift key when stating but still nothing I've also tried all the other command key techniques and still nothin. While its the folder ? Keeps flashing I hear it makin noise like the normal noises it makes when stating up or performing other tasks what is the problem? It was working fine then I got a message telling me to reset and then I get this I don't know what happened?