WD aknoledges the problem with the models: WD20EADS, WD20EARS, WD15EADS, WD15EARS, WD10EADS, WD10EARS, WD8000AARS, WD7500AADS, WD7500AARS, WD6400AADS, WD6400AARS, WD5000AADS, WD5000AARS

Then, it directs you to download the wdidle3 as a fix. BUT they didn't updated the wdidle3 page to reflect those new models:
This utility is designed to upgrade the firmware of the following hard drives: WD1000FYPS-01ZKB0, WD7500AYPS-01ZKB0, WD7501AYPS-01ZKB0.

CAUTION: Do not attempt to run this software on any hard drives other than what is listed above.
One WD representant said that this information is outdated, and that it would be changed.... 10 months ago: http://community.wdc.com/t5/Desktop/...ght/true#M1113

So, if something goes wrong when I'm trying to fix their drives with their tools, I might have problems with the warranty... even thought it is reported working by lots of people, even by an WD representant.