USB drive stuck on read only
Plug the USB drive into any Windows computer.

Navigate to "My Computer" in Windows Explorer (click Start->My Computer[near the top right of the window]).

Right-click on the USB drive:


Windows 7:

Should be listed under "Devices with Removable Storage"

Windows XP and older:

Should just be listed in a list of all drives installed on the computer



Click "Format".

Choose options you want to format as, make sure the "Read Only" button is deselected, and make sure the "Hidden" button is also deselected, and click "OK".

Congratulations! Your USB drive has now been re-formatted. You (should) now be able to format it using Mac OSX.