ntfs - dd clone hard drive: Input/Output Error though "chkdsk" says OK

I've used dd to clone hard drives before using 'dd' and a live cd, but have run into a problem.

The issue:

dd fails with an "Input/Output Error" on /dev/sda3 , even though windows "check disk" (chkdsk) says it's ok.

Context:

• Trying to replace my laptop hard drive w/ a faster one of the same size


• Laptop has NTFS on a 320gb hard drive


• Booting into knoppix


• Knoppix recognizes 'original' drive(/dev/sda)


• I am using a usb connection for ‘new' drive (irrelevant, but just an fyi)


• Knoppix recognizes the usb drive as /dev/sdb


• 
  

  Using dd, as follows:

  
  

  dd if=/dev/sda of=/dev/sdb

  
  


• 
  

  `dd gives the I/O error above at 82Gb (out of 320Gb)

  
  


• 
  

  I then tried checking each partition as follows and found it failed on /dev/sda3:

  
  

  dd  if=/dev/sda1 of=/dev/null
  dd  if=/dev/sda2 of=/dev/null
  dd  if=/dev/sda3 of=/dev/null 
  



• 
  

  I have ran windows xp chkdsk on the offending drive in both "find only" and "find and fix" mode and it reports no errors

  
  

Question

How can I find and fix the error on my original hard drive partition (i.e. /dev/sda3) so that dd reads it successfully?