What am i doing wrong?

[Khyron320]

I just lost my 2nd western digital 120jb out of 6 in 1 month

1st drive was november 2002
this next one was from may 2003

i have the system power these drives down after 2 hours of inactivity

I have a quality power supply VANTEC 520
and a quality surge protecter from belkin.