A Drive gone wild

Although new to this inustry I’ve seen a few good problems. Here’s one icould use some help on: I have several machines in our network that have recently begun acting strangely.. The A: driveseems to have a mind of it’s own frequently at boot up they kick in (no disk)not unusual, but thoughout the day they just keep kicking in for no reason. It’s not the word processor- it happens with no program running. Any ideas?