Chapter 15 PC Troubleshooting 645
✔ Invalid partition table.
✔ Error loading operating system.
✔ Missing operating system.
If any of these three error messages appear, you most likely have a hard drive
problem. To check, try booting the system from a floppy disk. If the system boots
normally from the floppy, this will verify a hard drive problem.
Mechanical Hard Drive Failure
Mechanical parts wear out. A sure sign of an upcoming mechanical hard
drive failure is an unusual sound coming from inside the computer when it is
being accessed (a read or write operation is being done). The sound may be a
high-pitched whining sound or a clanking sound. The strange sound coming
from the hard drive is mechanical in origin and cannot be repaired. Swapping
out the bad hard drive is the only solution.
The only guaranteed method of fully recovering from a hard drive failure
is by doing regular backups of the data. You can always reinstall a collection of
software when replacing a hard drive, but the data will be lost unless a recent
backup has been made. Users should be instructed to back up data regularly, but
it is even more important when a hard drive makes strange sounds. Data should
be backed up immediately, and a technician should be called to prepare for the
crash. You should have parts on hand and be prepared to replace the hard drive.
MBR Failure/Recovery
Hard drives can also fail because of corrupted files and data. The most
important area of the hard disk is the master boot record (MBR). If the MBR is
damaged, the hard drive will not support the booting process. However, you
will still be able to boot from a bootable floppy or CD. Once you boot from the
floppy or CD, try to look at the hard drive by entering the
dir C:
command at
the command prompt, Figure 15-4. If you can view the files on the hard drive,
then you are in a position to do a repair. You probably will be able to remedy the
situation. As a precaution, back up all data immediately.
You will not be able to back up the files in every situation. But, if you can see
files on the hard drive, you should be able to back up important data to some
kind of data storage media. Generally on an older system, you will be forced to
do a copy to disk. Though, on some newer systems, you may be able to access the
drive via an existing network connection. A modern computer with a bootable
CD-RW allows for a quicker and easier backup of system files. You can boot
the PC using a system restore CD. The CD is placed in the drive and loads all
necessary files to boot the PC. In addition, you may load a driver to support the
CD-RW. After the drivers are loaded for the CD-RW, you can copy files that need
to be backed up.
Avoid using the
fdisk/mbr
command unless it is as a last resort. The
fdisk/mbr
rewrites the boot code portion of the MBR. The last two bytes in the MBR contain
partition and volume information. If the last two bytes in the MBR were deleted
by a virus, all partition information will be lost when you use the fdisk/mbr. Two
situations are made worse by this command. One situation is when you have a
multiple boot system using at least two partitions. The
fdisk/mbr
command can
make the second partition inaccessible as well. It overwrites the partition table,