"Phantom" Threat: Can't Locate It, so Can't Remove it

I am running Norton Security on Windows 7 Home on my desktop machine. I have several external drives connected to it.

During a full scan it appeared to flag a threat called "movtomp4_setup.exe" in my I drive which had been connected but usable for months, probably because of hardware failure. I had not disconnected it from the machine yet because, frankly, laziness.

Unfortunately, Norton was unable to remove the threat, and since I could not get into the drive to remove it manually, I simply disconnected the drive.

However, when I restarted the machine, it flagged the same threat in the same drive, even though the drive is no longer connected.

There's something else strange, though. NS indicates that the threat is present in two locations: the original (and no longer connected) I drive location; and someplace referred to with several underscores: ___. I do not know what that is.

Has anyone seen this problem before and can offer a solution? I have a screenshot on the attached PDF for you to review.

Thank you.

Chuck