Reformat Internal Hard Disk

1. Disconnect any external SCSI devices and reboot.
2. If the problem persists, format the internal hard disk.
3. Access Format function: Press Master/Global, then 77 on the numeric keypad.
4. Select the hard disk and confirm formatting.
5. If reformatting fails, consult service center.

Source: Emulator III XPs — e-mu-emulator-iiixp-operations-manual (manual)