What is the hard drive?  Well think of the hard drive as your brain.  It's where all the information is stored.  Just like you as a human being retain memory, your hard drive does the same thing.  The Hard Drive contains your OS (Operating System)  or your version of Windows.  So it's very important to have one in good working condition.  

Having a hard time diagnosing a bad hard drive?  You can use this system for a free diagnostic check over the internet, it will tell you diagnostics for the whole system.  Click here to try it.

Here are some symptoms you might have:

You turn on the computer but it says "Operating System Not Found"

You turn on the computer and it says "Invalid System Disk"

You constantly lose information and your programs crash all the time.

To test the Hard Drive for possible failure you can run a scandisk.  It is best suggested that you run a scandisk thorough.  Sometimes if you run scandisk regularly in windows it will tend to restart several times and take extremely long to scan.  You can help prevent this by starting your computer in "Safe Mode"  All Windows systems have a special diagnostics mode call Safe Mode.  To get into safe mode you will need to restart your computer or turn it off then back on again.  While starting up you need to press the F5.  For Compaq and Hewlet Packard Computers you will need to press this key when you see the manufacturer's logo.   For hp it's the first blue screen you see for compaq it's the first red screen you see with Compaq.  For all others you should see something like bios or cmos screen you should start pressing F5 then.  You'll know when you are in safe mode when you enter Windows and it says SAFE MODE in all 4 corners or it may just tell you at the beginning this is safe mode.  Now let's run Scandisk, click on START then PROGRAMS then ACCESSORIES then SYSTEM TOOLS then SCANDISK.  When you open the program you'll have two options.  Scandisk STANDARD and Scandisk THOROUGH.  You will need to chose Scandisk thorough.  Chose start and let it run it's course it will tell you at the end what errors it finds as it scans sector by sector.  If it restarts 10 times you may have a virus on your computer you  will need to scan your computer for viruses.   To determine if the hard drive is failing you may need to run scandisk a total of 3 times and if all 3 times return errors you have a failing hard drive.  

Disk Boot Error

If you can run a startup disk and get to the c: drive you should be able to boot on it.  Could also be a boot virus.  If you can't get to your Hard drive  you can try to get into your setup or cmos to see if it may be disabled.  Best thing for that is to reset defaults or restore defaults.  Usually this takes care of it.

For HP Computers Look beside boot devices and see if Hard drive is disabled.  If so Re-enable it.

Hard Drive Utility Programs 

| wdclear | -Description :  Write zeros to the hard drive