You have two kidneys, each about the size of a fist, located on either side of the spine at the bottom of the rib cage. Each kidney contains about one million functioning units called nephrons. A nephron consists of a filtering unit of tiny blood vessels, called a glomerulus, which is attached to a tubule. When blood enters the glomerulus, it is filtered and the remaining fluid then passes through the tubule.
In the first case, each time the computer starts up, the question mark appears and flashes for a few seconds, then disappears. The cause of this symptom is that there is no hard drive selected in the Startup control panel. Remember that selected on the Macintosh means that an icon is darker than the other.
1 Answer from the Community. when the light on front blinks yellow it means that there is a problem, it can happen for a number of reasons (No network connection, software update etc...) all you have to do is open airport utility on your computer and it will tell you what the problem is! simple as that!