Thanks for posting. I’ll be glad to assist.
I think a good place to start will be to determine a bit more about the drives in use - what they are named, vs. what their assigned drive letter is. There’s a difference between what a drive is named, and what letter Windows assigns it.
You should be able to right-click on the drive letter, and select “Rename”. This will allow you to rename it whatever you’d like (“Norman’s 1TB Drive”, etc), though this is independent of what drive letter Windows will give the device.
Windows should be able to run many drives simultaneously without having additional drives cause existing drives to go offline, so tough to say what’s causing that. If both have been assigned the same drive letter, then only one drive will be visible. So it might be worth trying to manually set the drive letters of the various drivers.
Changing the actual drive letter requires a more involved process, which is covered step-by-step here:
You probably won’t want to change the drive letters of internal drives, since programs that are installed on those drives will need the drive letter to remain constant. But manually changing the drive letters of the external drives will be a good starting point.
If that doesn’t help matters, please email email@example.com and we’ll have a look at some log files to see if we can determine any other potential causes of this behavior.