Hi Pierre Tremblay,
First order of business is to secure your data. You've tried but not been completely successful. You might want to try selectively copy of files instead of the entire folder. There might be a bad spot on a drive, and if you selectively copy files it might just copy around the bad spot.
Then you can run the diagnostic if you like to test the disk drives in the HMV. Here is how:
http://kb.ciprico.com/lore/article.php?id=236
Or you might have to send the unit in for service. Please give us a call or email support@ciprico.com with the serial number and model number.
Robert Leong - Tech Support
Huge/Ciprico.