hard drive or monitor randomly switching off ?

This problem could be that your Power Options in the Control Panel have been switched to "switch off the component ever now and then to save power". To change this, do the following:

1) Navigate to the Control Panel by clicking Start and then Control Panel. Then double click on Power Options as shown below circled in red.

2) This will then display the Power Options window as shown below.

3) Once you have opened the Power Option Properties, under Power Schemes select the one that best suits your PC system.

4) Then you can select whether or not to switch off your monitor and/or hard drives after a period of time when it is not being used.

If you have your PC on most of the time then I suggest you select Never as the turn off option for both your hard drive and monitor. If you are using a laptop the turning off the hard drive and screen can however save on battery power when the laptop is not in use.

If your problem persists then it might just be as simple as a loose connection, make sure all hard drive connectors are firmly inserted and that your monitor display plug is correctly plugged into your display card or onboard display correctly.

If your hard drive persists with this problem then it may be a faulty dive. I suggest you take the drive to a PC technician and have them check if it's faulty or malfunctioning.