Easy fixes for computer operating system issues

Operating systems are  essential pieces of software that manage your computer and start up automatically. If they fail to load correctly, try the below tips to get your computer back on track.

Check for external issues

Do you get a "Missing operating system" message (Windows) or a blinking globe or question mark (Mac OS X) when your computer starts up?

• Eject any CD or DVD that you may have left in the drive and disconnect any external hard drives, flash drives and devices, such as scanners and printers, connected to the computer. Try restarting the machine.
• Make sure nothing is resting on the keyboard. Try unplugging and reattaching both the keyboard and the mouse.
• Does your computer beep when you start up? These beeps are the audible result of a self-test routine and indicate some kind of problem — a failed memory card, for example. Make a note of the number and duration of the beeps (short or long) and, armed with this information, talk to an expert: the nature of the beeps is a very useful clue to what's wrong, but it needs skilled interpretation.

Jog your computer's memory

If Windows or Mac OS X still refuses to boot when you restart, your computer may have forgotten the correct startup sequence. The part of the computer's memory responsible for this is located on the motherboard — usually the largest circuit board in the computer, which holds the processor, as well as slots for the RAM cards and graphics and sound cards. The memory is powered by a small battery that maintains the memory even when the machine is switched off.

• Turn off the computer and unplug the power cable. Open the computer's case and locate the battery on the motherboard. In most PCs, this is a CR2023 coin cell that resembles a watch battery. In some computers, it may be a small, barrel-shaped cell. Remove the battery and wait 20 minutes before replacing it, closing the case and attempting a restart.
• If you are a Mac OS X user, try restarting the computer while simultaneously holding down the following keys: Command+Option+P+R.