1. You may be using a USB storage device with a large consumption current. (If a current above the allowable level flows in the USB device, a caution appears on the CDJ-900's center display.)

Use USB devices with a power consumption within the CDJ-900's rating of 500 mA. Also, use an HDD for which power can be supplied externally with an AC adapter, etc.

2. The format is not supported on the CDJ-900. Format in FAT16, FAT32 or HFS+.

3. The CDJ-900 does not support the GUID partition map Mac OS standard format.

4. USB storage devices formatted with "Distinguish between capital/small letters" set for the Mac extension format may not be recognized.