Spontaneous unmounts of MyBook Essential 2TB

Since this week I encouter spontaneous unmounts of my MyBook essential 2TB (USB3 version) on my iMac running Lion 10.7.2.

I use this disk a year without any problems. But suddenly, i think after a wd smartware and firmware update problems started. The updates went fine, but now there seems to be some sort of problem. 

p/n: wdbacw0020hbk-00

s/n: [Deleted]

please, really need help!

Ok have you test your drive in a different computer did you get the same results?

not yet.

but what I did, and it seemed to help a bit, is disable ‘Lion spotlight search’ on the drives and for now, turn off ‘timemachine’.

i will keep you informed.

the problem is still here. altough the drive does not eject within 3 seconds of mounting, but random from 1 minute to 1 day.