This could be caused if the USB connection and/or Network cables are not properly connected, or if there is a missing terminator.

To remedy this, check all network connections to make sure the CAT5 cable is inserted all the way into each jack. Also make sure you have two network terminators installed in your system so that all RJ485 jacks are in use. Confirm the USB cable from your computer is connected to the front left speaker (the speaker with the Left DIP switch in the "on" position.

This troubleshooting item can also be found in Appendix F of the Owner's Manual for the LSR4326p and LSR4328p.