Can't format a drive using partition magic

Have you attempted any alternative methods to test this drive?  Say on another device or with a USB adaptor or another adaptor to see if the drive can be read?

How about testing it with the MFG drive tool utilities?  Each MFG of HDD provide a testing tool to validate a drive and if it is found bad, and under warranty, a return can be generated...perhaps test with this method before using with Partion Magic.  

Otherwise, my experience has been the drive set up wtih PM is pretty straight forward, and I wonder if your drive is indeed bad.

Also,

Please provide the exact OS you are using (Windows XP Pro, home, Vista Pro/home, 7 ect...)
Is this a custom built box?  Brand (which one)...provide model #
And the drive brand/mfg would be helpful unless you are able to locate the MFG tool on your own.

Also, could you describe how you installed this problem drive?   Is it Slaved or Cable Select?  Is it SATA or EIDE (or even SCSI...but I doubt it is).   Internal or External (though guessing internal).

Thanks

the external drive , is the primary drive of one of my laptops.
I have tried to reinstall windows 7 on it, but i have couldn't, so I decided to purchase an external hard drive enclosure.
I am trying to format that drive to be able to reinstall an OS on it.

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windows xp : OS where partition magic is install
windows 7: Os that was installed on my external harddrive
brand of the hard drive ; western digital
model number : WD6400BEVT
disk type: sata

Thanks for the info:

You may wish to start here with this utility from WD:
http://www.wdc.com/en/products/products.aspx?id=140

Follow the questions on the right-hand-side and it should allow you to download the correct version.

i recommend to install the drive in the laptop, and run the diag as said by Plantwiz
if it is ok, you should be able to  install W7 again  -no need to formoar before
if you want to erase the drive completely, BEFORE anything else, download UBCD, and run dban, or any eraser tool :
http://www.ultimatebootcd.com/      

I have used acronis partition expert, and it worked!!