Windows 7 - External hard drive not showing up in Windows Explorer

I am having a strange problem with my external hard drive for my backups. When I plug the drive in, it does not show up in Windows Explorer. I can make it show up by going into disk management and assigning it a drive letter, but the next time I plug it in, I have the same problem again. Any ideas why this might be occurring?


Edit: Turns out this is not limited to my backup drive. Once I assign a letter, the drives work fine. They will even keep the letter if I eject them and re-insert the USB connection, but any external media I plug in fails to assign a drive letter automatically the first time it is plugged in. While I do not see this as a huge problem, it bothers me that Windows is not working as it used to nor as it should.

Edit2: After reading some of the related forums, I realize I should be clear about a couple things. I am having this problem with drives that have already had their drivers installed in Windows. I do not get a dialog saying that Windows is installing these devices because the devices have already been installed. For some reason, their volume letter has been forgotten by Windows and I have to re-assign it. I am being careful not to use the same letter more than once. I am plugging the drives in while Windows is already running.


Any help would be greatly appreciated so that Windows will automatically assign a drive letter to a device instead of me having to manually do it when Windows forgets what letter it had assigned.

Windows 7 x64 Quit Assigning Drive Letters Automatically helped me solve my problem. Ran an Elevated Command Prompt and typed the following commands.

mountvol.exe /n
mountvol.exe /e

Guess it just needed to be reset by disabling auto mounting and re-enabling it.