Network drives are mapping themselves

I currently have one drive (N) mapped from my company's network: "Main Server\\Work Data\Document\Pictures" Starting last week, at least a few times per day, I see that there are new drives mapped to "Mainserver\\Work Data" - this folder *used* to be mapped to my computer, but it was disconnected over a month ago. The drives are somehow mapping themselves. It start with the Z-drive, then...