[Elecraft] Problem with 100W PA

[N1IX]

I noticed that my power output would not go above 80 watts on the display so I finally decided run the "Calibrate Transmitter Gain" selection in the K3 utility program.
The 5 watt calibration runs fine with no problem. When I run the 50 watt calibration I get a number of errors. The first is "CheckSwr: Unexpected response "" to "DS;" State 151.
Which is followed by a number of error messages. 
Now the K3 trips off whenever I try to use more than 40 watts.
I have tried everything that I can think of.
Both antenna connectors
Two different dummy loads. 
Different cables both RS232 and Coax.
Powercycle the K3. 
Even rebooting the computer. 
Has anyone else experienced this? Any suggestions?

Dave N1IX