Reboot (restarting the computer system) is an all-time techie favorite
suggestion for all sorts of a computer problems. Reboot returns all the
software and most of the hardware to some known initial state, thus
eliminating any intermittent problems.
How to properly reboot a system
If you are troubleshooting some major problem, you sometimes need a
proper reboot procedure.
Shut down. Everything.
Shut down the computer
Shut down all the peripherals which have their own power.
This includes external hard drives, CDROMs, printers.
Some say that the component is properly shut down only if
there is a visible discontinuity in its power line. That means
you pull plugs from their outlets for all components.
Note that LED lights may be still blinking for about a
minute after you cut the power. This is normal.
Connections.
Disconnect data cables for all the peripherals you do not
need (read - everything except keyboard, mouse, and monitor).
If you are going to recover data from the external hard
drive, remove and then reconnect its data cable. Ensure proper
connection.
Turn on.
Peripherals first. Turn on devices which have their own
power. There should really be a small number of these.
Once the peripherals are turned on, wait for them to
complete whatever initialization they may need. A couple of
minutes is typically enough.
