Three times this morning, immediately after starting the 6500 & SmartSDR the radio locked itself in transmit at the first touch of the CW key, necessitating powering off the radio, once requiring me to pull the DC power. At one point, the message appeared; "Shutting down. Error PSL13V8A-05,26. After waiting 5 minutes for it to actually shut down with no results I killed the power supply to force a shutdown. Coming back an hour later I rebooted everything and as I write this everything seems to be OK. What is the likely cause of the problem and/or what is the error message telling me?