Turn off your computer and make sure it powers down

P.C. Periodicals

Do not turn off your computer with that physical power button. That is only a power-on button. It is very important that you shut down your system properly. Simply turning the power off with the power switch can cause serious file system damage. While the system is on, files are in use even if you are not doing anything. Remember that there are many processes running in the background all the time, and using the power switch does not allow the graceful shutdown of your computer.

The real danger of blackouts, brownouts, and using the computer’s power switch is the "unexpected computer shutdown." Operating systems are complex and they must go through a “shutdown sequence” to make sure all running processes have correctly terminated before powering off. A sudden loss of electricity can interrupt important threads and leave your computer in an inoperable state.

System files are the largest concern. Consider what happens when a hard drive is writing data to the disk but suddenly shuts down in the middle of it. Suppose the file being written was a system file necessary for the booting process? Now that file is corrupted and you cannot boot up your computer without going through an involved recovery procedure.

Furthermore, frequent power outages can reduce a hard drive’s physical lifespan. The read-and-write head, which hovers over the spinning platters during operation, snaps back into its original position upon power loss. This sudden movement can cause tiny imperfections that accumulate over time, increasing the likelihood of a “head crash” (a malfunction that occurs when the head touches and scrapes the platter surfaces, effectively destroying the hard drive).  Solid-state drives can also suffer catastrophic damage from sudden power cuts. Issues can range anywhere from data corruption to total malfunction.

There is a lot of discussion on the internet and from "computer advisors" that there is really no problem using the power switch to turn off your computer — they are wrong!  This is why they are wrong. Let us look at what really happens during a normal shutdown.

There are a lot of things happening during the shutdown process. Here are just a few examples of what happens when you request your computer to shut down:

• Checking to see if any user applications have not been closed yet (like an unsaved document) and prompt the user if necessary;
• Stopping background services;
• Waiting for the termination signal from services and applications that are open or running;
• Flushing the cache to disk;
• Writing log files;
• All users are logged out;
• Ending the operating system shell;
• Start installing Windows updates and tell the system to finish the update process during the next system startup, if necessary;
• Updating the system registry;
• Send the ACPI shutdown signal (this is what turns the machine off).

These processes are not performed during the unexpected power termination (blackout, brownouts, and using the power switch.

Is unexpected shutdown harmful? 

While your hardware will not generally be damaged during an unexpected power shutdown, the contents of your disk drive will most likely be damaged. Holding the power button down is no different than an actual power interruption as far as the computer is concerned.  If you are working on any files when things go bad, then at a minimum you will lose your unsaved work. Beyond that, it is also possible that the shutdown will cause data corruption in any files that you have open. This can potentially make those files behave incorrectly, or even make them unusable. While unlikely, it can be a major inconvenience if it does happen, and the risk serves as a reminder of the importance of backing up your data regularly.

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Besides corrupting your computer system, program, and data files, the disk status of what locations are available on your disk drive may now be invalid.  Restarting your computer after an unexpected power termination can cause the computer to write over previous assigned portions of your disk drive, and most likely you will not find out until later date that something has been corrupted (destroyed).

Proper method for shutdown

In any case, when you want to reboot or power down your computer, it is important to do so properly. Since a shutdown and a restart are similar procedures, most of the ways for powering off the system can also be applied to restarting.  So what is the correct way to turn-off a computer?

• Step 1: Click the 'Windows' button at the bottom left-hand corner of your screen.
• Step 2: Click Shutdown or Restart.
• Step 3: Wait for the system to power itself down, or start the reboot. Done!

If you have every had an unexpected power termination, most likely your disk is corrupted. If a repair has not been performed immediately after such an outage, the corrupted disk will eventually start causing problems and you will know that by "My system is frozen and it is not responding." Remember that early comment about not finding the corruption until a later time — well you may have just found that time.  However, not all "frozen systems" are caused by a corrupted disk drive.

How to shut down a 'frozen' computer

If you are using a desktop or laptop running Microsoft Windows, chances are the computer will run flawlessly but what do you do if your computer crashes and becomes “frozen”? While a frozen computer can be a symptom of a serious issue, there are steps you can take to attempt to recover your system.

Many Windows’ crashes are caused by programs that have become unresponsive; simply waiting a few minutes often will allow the program time to recover. If your Windows computer is still locked up and unresponsive after waiting, then the following steps should help you restart your computer.

The first thing you should try is to end the program which has caused the freeze. You can do this by using a program that comes with Windows called Task Manager. Press CTRL+ALT+DEL at the same time and the Task Manager should open. Task Manager shows a list of all running applications (now called processes) on your computer.

In the list of running programs, you want to look for any programs that say “not responding.” If any program is labeled “not responding,” right-click on the program in Task Manager and select “end task” from the menu. This should close the unresponsive program. If a popup window asks you to “end now” or “wait for the program to respond,” choose “end now.” You may lose any work that you had opened in this application.  Unfortunately, if this option fails, most people use the power switch to recovery and now more damage may have been done to the contents of the disk drive.

If a disk repair is executed immediately after unexpected power termination, there stands a good chance to fix the damage disk drive.  However, restarting the computer (without the repair utility running) will most likely prevent the recovery of the disk drive. This process will generally work if performed on the very first unexpected power termination event, if was not performed the first time, the chances of success are greatly diminished.

There are various ways to invoke the repair utility, the easiest being to boot from a Windows installation disk. Using the repair function on the installation options, use the command prompt to invoke the CHKDSK repair utility (be careful here — the wrong choice with the installation disk can wiped-out your entire system).

Later Windows system include a second bootable system that does not use your c-drive as the boot drive. Starting with this system allows errors to correct the errors on the c-drive, but it may take several hours to repair.

When using the command prompt from either method, it is a good idea to run the CHKDSK utility in read-mode first. Read-mode simulates the repair process without making the repairs and generally only takes a few minutes to run. 

If the CHKDSK utility fails to complete, that generally means that your disk drive has a major problem and is badly corrupted and a reinstall may be required.  If the read-mode completes successfully, the CHKDSK can be rerun to repair the disk – this process cannot be interrupted or everything may be lost on the disk.

When running CHKDSK in read-mode, comments will be issued by the program in relation to the status of the repair, the message at the end is what is important.  One of the error messages generated by CHKDSK is "The Master file table's (MFT) bitmap attribute is incorrect." Here is an example:

The master file table's (MFT) BITMAP attribute is incorrect.

The Volume Bitmap is incorrect.

Windows found problems with the file system.

How to fix CHKDSK error in volume bitmap

Since the error occur in Bitmap attribute, it can be resolved using CHKDSK command as CHKDSK C: /F

In the disk file system, a file called $Bitmap consists of a large array of bits that specify the used & unused disk clusters in a volume. This file is located in Master File table (MFT) and when a file is created, its location is marked in this bitmap file.

Causes of the error 'MFT bitmap attribute is incorrect'

There can be many reasons why Check Disk utility encounters the error 'volume bitmap is incorrect'.  Some of the reasons are hard disk failure, bad sectors, corrupt Bitmap attribute, corrupt empty space in $Bitmap file, sudden power failure, and virus infection.

The main reason behind this error is that when the system function Volume shadow copy (VSS) gets invoked then it may be possible that volume bitmap values do not accurately reflect the used clusters. Therefore, data could be saved in a corrupted state.

But if you keep getting the same error whenever CHKDSK is run then it means CHKDSK is not able to repair the corrupted files. Additionally, if you are compelled to format the disk due to corrupted files then the data will definitely be lost. It may be time to call a technician.

You now know why I say that some people are wrong when they say it is OK to use the power switch.

Stay protected!

George Cox is the owner of Computer Diagnostics and Repair. He can be reached at 702-346-4217.