Removable today, unremovable tomorrow? (partiallyOT)

So, here’s this laptop. It runs W2K pro. It has a drive bay. From the day it
was born until quite recently, the drives in the bay (each contains a
flopsical and a CD of some sort) showed up as an ejectable device.

Suddenly, they are no longer removable if they are in the beast at boot
time. If I boot with the bay empty, and then insert, the drive is removable.

Any clues? I propose to excuse myself that this poses a question that is
interesting to the people who build drivers for things like this.