Scan a Drive for Errors with HD Tune
If you suspect one of your drives contains damaged blocks you can use HD Tool a Windows tool to check for them. The interface is simple to use and understand. Keep in mind that scanning and entire drive for bad blocks will take a long time and possibly hours. If HD Tune finds any bad blocks it will report them as a percentage. HD Tune can be downloaded from http://www.hdtune.com/download.html, there are two version available one is paid, the other is free (this is the one you want).
How To
Scanning for bad blocks is as simple as starting the application and selecting the drive you wish to scan from the drop down list. I will be scanning my WD 640GB hard drive. 
After the target drive is selected click on the Error Scan tab. 
Click on the Start to start the scan. 
The scan might take a long time, it all depends on the size of the drive to be scanned. 
The scan yield no bad blocks, the green blocks represent good blocks. In the event bad blocks are discovered they will be represented as red squares. 
Conclusion
Using HD Tune to discover bad block is quite easy thanks to the simple interface, this sort of operation will always take a considerable amount no matter what. If your scan yield multiple bad blocks then I recommend backing up the data and migrating over to a safer drive. Comments are always welcomed.
Links
bad block, hd tune — Jul 23, 2012