My Book Studio II Losing Partition on Lion

I’m running the My Book Studio II as a single 2TB partition connected via Firewire 800 to a Mac Mini running Lion.  On two occasions now the partition simply disappears and will not mount.  The drive is visible through Disk Utility and the partition is greyed out.  I can reformat the partition and start using it again without issue.  However, this has now happened twice in the last 2 months.  Thankfully I had a full backup, but this shouldn’t be happening.  Any suggestions?  The drive is only 6 months old.

I have a similar problem. I was using my My Book LX without any problem with Lion up until today when I decided to add a password. 

I am using a MacBook Pro. I have upgraded Lion from Snow Leopard. The transition was OK. The drive and Time Machine worked OK. 

This morning, I turned on the security/password feature on the WD SmartWare software. I remounted the drive. Then, my My Book partition disappearted. After I removed the password feature, it came back, but now it appears in grey in DiskUtility but does not mount.

Any help? I hope that I didn’t do anything wrong with the password feature 'cause I don’t have any backup.

Please help.

I hadn’t done anything with the password.  It simply disappeared through normal use.  I guess the MacMini started up yesterday and the partition was gone!

And now it’s happened for the third time.