R&S CMU200 hangs when the RF generator output is turned ON

[electronic_guy]

Hi,

In my CMU200, when I clicked the ON/OFF button to turn ON the RF generator, the whole thing get stuck and the whole button panel becomes non-responsive. The only thing I can do is long-press the power button to reboot it. I'm not getting any error message on the display since the whole thing gets stuck. When I kept the CMU200 running for a while with stuck generator the fan starts to work with a loud noise. Like its angry for letting it stay stuck . maybe something heats up when it get stuck like that. I'm not sure. So I'm clueless as to why this happens. 

Please help me to sort out this problem.

Thank you.

[R-1125F]

Does it run self tests OK?   Have you changed the battery?