i also have the 7200.11 series. 500gb and 750gb.
first i had a 500gb 7200.11 which failed which I then RMAed and they gave me a new 500GB 7200.11 which began to show failure 1-2 months ago. then i bought a new 500gb 7200.12 thinking problems are fixed.

unfortunately, im stuck. sigh. just within a week, im having problems with it. I try to copy paste between different hard disks, after a while it started to give like a beep sound. not a click sound though..

the 750gb 7200.11 harddisks are still working at the moment but not sure when those are gonna fail. Sigh.

i have a 160gb seagate hdd but that's been much more reliable than all the other hard disks.

western digital from now on.

i'm on the sd15 which has already brinked. gona send it in for rma or something and get a new hdd and sell it