The drives are properly identified in the Explorer Folders window as Removable disks. If there is no media in the device, you get the following message when scrolling the "Folders" window brings the drive into view (the message actually pops up just before the drive would be displayed):

Message box caption: Explorer.EXE - No Disk
Big red X followed by "There is no disk in the drive. Please insert a disk into drive \Device\Harddisk2\DR4.
Buttons: Cancel Try Again Continue

The message shown is for the Olympus reader. The message shows different details when there is no zip disk in the zip drive.

If you keep using Explorer by clicking cancel or continue, it eventually crashes. The Dr Watson log shows an Exception Number c0000005 (access violation).