REMOVABLE DISCS FROM OUTER SPACE

I am running Windows 2000 on a new Pentium 4. My computer came with CDRW. I moved it to slave and installed a new DVD-CDRW Combo drive as master.
They both show up, but the combo disk is Drive “D”, the CDRW is Drive “I”.
In between, all these drives— “E”,”F”,”G”, and “H”— suddenly showed up. They all just say “Removable Disc” Why are they there, and how do I get rid of them?!