I found this on Google:
"MSCD001 or MTMIDE01 are not files but instead a name associated with a driver. An example of what may be seen in your autoexec.bat or config.sys may look like:
the /D:MTMIDE01 is not a driver, it is a name associated with a driver, and when that driver loads it will then be given the MTMIDE01 name. In the above example the name of the driver is MITSUMI.SYS.
A computer can receive an error that MSCD001 or MTMIDE01 may not be able to load either because the MSCDEX.EXE driver is missing or corrupted or the CD-ROM driver is missing or corrupted and therefore cannot be loaded and the name cannot be associated."
but I have this in my config.sys (A: drive):
and it happens with two different startup disks.