MacBook Pro is restarting unexpectedly. Please Help

My MacBook Pro 2010 keeps restarting (at least 3 times back to back) when I turn it on-- as well as when I open certain apps like iPhoto. Does anyone know why this is happening? The hardware checked out ok at the apple store when I had it diagnosed yesterday. Also, I had Geek Squad do a remote in session and they said it could be the video/graphics card. Computers are definitely not my forté so I would appreciate any advice. Please help:-)