+ 0 Votes You can 'allocate' a letter for the drive ... OldER Mycroft 4 years ago Although, from experience, I find it much better to give each external unit a NAME. That way it doesn't matter what letter they're allocated, the name is how you tell them apart. + 0 Votes Win 7 changing drive letters estephen4 4 years ago Thanks for your response, but it doesn't really address my issue. I have already allocated a drive letter thru disk management. My problem is Windows changing the drive letters whenever I plug in an additional usb drive, such as a flash or mp3 player. This in turns disrupts other software which uses the drive letters for copying files.