Generally this can be caused because "dual wire" was unintentionally turned on. The best way to correct this is to restore defaults, then re-establish the required front panel settings. Here are the steps to restore defaults:
1. Power down the Aurora
2. Pull the AC power cable
3. Press and hold the Sample Rate button while plugging the unit back in.
4. Wait about 2 seconds, release the Sample Rate button
5. Power up the Aurora with the front panel switch.