it's not about any drive letter limit it goes from A to Z (beginning with C for harddrives)
I would say only one drive is recognized. Unplug them and try to plug them back in, in the opposite order one at a time.
BTW: Did you ever open one of those "CD drives" to see what's in there?
It has( amongst others) a file called "What is this.html" which starts out like this:
Quote:
About the Western Digital® SmartWare™ Virtual CD
The WD SmartWare Virtual CD (VCD) included on your WD hard drive mimics an ordinary physical CD that is indistinguishable to your hard drive. The WD SmartWare VCD contains the software you need to start using the WD SmartWare software to organize, back up, retrieve, and secure your files as well as other essential information, and has the additional benefit of avoiding wear and tear, damage, or loss of a physical CD.
In addition, updates to the WD SmartWare VCD, when available, are automatically downloaded from the web to your drive so you don’t have to wait for the arrival of a physical replacement CD.
-DG
Edit: Oh we cross-posted

you just posted the screen print and see drive 2 is shown as offline
try the replugging (directly into the computer if you can)
-DG