Mt. Lion upgrade causing problems with WD Elements

WD External Drives External Drives for Mac
4

I have a mid 2011 imac too

Two FW800/400/USB2  disks, model wd4000mt

usb work fine.

fw800 not work very well in lion and mount lion in my mid 2011 imac

via port fw400 in my old imac and macbook with snow leopard work fine