What does the "mci device" or "mmsystem" error mean?

These errors indicate a Windows-level communication issue with the CD-ROM device. Common causes include:

• CD-R writing software that locks the device
• Another application that has exclusive control of the drive
• A general Windows media control interface issue

Try rebooting the machine to resolve this. If the problem persists, close any CD burning software that may be locking the drive.