Padlock Symbol at Lower Left of USB hard drive Icon - What does it mean ?

I have the same problem all of a sudden! Can anyone help? An external firewire drive which holds ALL my video and music mysteriously became locked to me today! I have run disk repair, logged in as both administrator and root, shared folder is checked AND ignore ownership is checked. Still, I am unable to access the disk or change the permissions to "read and write". It is a Western Digital 1TB Disk which has worked for 6 months. I don't even know how to lock it if I wanted to. Please, can anyone give me a clue? All my TV, Movies and Music are on this disk. HELP! (Thanks in advance)

Jumping on the band wagon here. I too have just encountered the exact same problem. AND to compound matters, when I try to copy data either "to" the drive(s) affected the copy process hangs and I am unable to stop or cancel the copy process and end up having to do a hard reboot. Any help in getting this resolved would be greatly appreciated.

I too want to join in on this Band Wagon! I did nothing new to my Mac Pro running Leo 10.5.2 and all current updates applied. First thing I noticed was copying files from an external usb drive. The file would get to almost finished and have maybe a couple of bits left. Then a notice would appear saying the files were corrupted. (NOT) I had to Force Quit the Finder and Relaunch it in order to remove the warning notice off of the desktop. Then I noticed 1 of my 4 internal drives with the padlock on the lower left hand side. As I was investigating that drive another drive blinked and then it too had the padlock! Now the external usb drive also has a padlock. I looked at permissions with (Command I) and found that my permissions had been changed to "Custom" which could not be changed back to read & write. In fact all of the affected drives now have the same issue. So to try to fix them I added myself to the users side of the permissions box and gave myself read and write permissions in the hope I could delete the custom permissions account. No Luck! But I was able to delete the new read write account? Ran Disk utility from the DVD an the drives still show up as being locked. Anyway when I removed the DVD I let the machine reboot. Now for the fun! It gets up to the grey background & spinning gears, goes to black and restarts. It stays caught caught in this loop until I kill the power. Call Apple support & they told me what I already knew. Reformat & start over. I do not find that to be an answer I want to know what caused it & how to fix it! Since my company just invested in 50 of these units and I am the only technician for over 200 users.

Same problem here. Three of my five drives are padlocked. I can only boot from my second bootable drive. Locked out of my own system and facing a -60002 error when trying to fix permissions.
Done nothing out of the ordinary prior to the problem.
Started when opening a file with Dreamweaver.The file I had create a week earlier in the same app appears as read only. Then Photoshop tells me my license is no longer valid and I need to reinstall. Frustrated, I reboot to a system with locked drives and messed-up ownership and permissions.Next reboot I am completely locked out.

Me, too. All my drives - internal and external all of a sudden had the lock symbol - I tried everything, and finally shut it down. When I restarted - I only get to the apple symbol, and that's where is stayed, until all the fans in my (MacPro G5 Dual Processor)started running and would not stop. Could not start up from CD - nothing would work. The computer is now at the Apple store while they try to figure out what the problem is. And - now when I plugged one of the externals from the 'sick Mac' to another G5 tower computer - IT STILL HAS THE LOCK ON IT! I can't figure out how to unlock this...

OK, I don't know the answer, but just a stab in the dark.
I had a similar issue with actual files on a USB drive, which I could not unlock or delete.
Turns out they were set to read-only by windows I use at work.
Plugged back into a Win machine, deleted - done.
So, Is there a chance your USB drives met Mr. Windoze recently?

Nooo - no Mr. Windoze - all Macs on the network. One drive was USB, two were Firewire. I'm still waiting to get my Mac back from the Apple 'hospital'... I'll post what answer I get from them when I get my computer back 😟

I'm not sure if you're still looking for an answer, but I had the same problem recently, and someone much smarter and wiser than me suggested, the following (and it worked):

run the following command from terminal (one for each drive)

sudo chflags nouchg /Volumes/"drive-name"

Put the name of the affected drive instead of drive-name in the above. keep the quotes. You'll have to enter your admin password (which you won't see). that's normal.

Good luck.

I think somewhere along the line these things got password protected?

I suspect you have some kind of permissions problem.
Have you done a file permissions check/repair?
Is the account you are using the administrator account or a standard user account?

Is or was that drive ever password protected?

Same problem here. Are there any solutions yet?

It seems like none of you have addressed the most obvious question... what happens when you Get Info on the drive and attempt to uncheck "Locked"?