the image froozen and the sound mut. Appear the message: The connection with the radio was lost.

Is your network connection wireless?  
Is the network monitor in the bottom right hand corner changing from green to some other color?

If you are getting disconnect messages, connection lost to radio, this indicates that the laptop is dropping keep alive packets for more than 15 seconds or that the radio firmware is crashing. You have have something corrupted in the the internal database that is causing the firmware to crash on band changes.

I recommend that you do the following.

1.) Power off the radio
2.) remove the DC power cable for 15-30 seconds.
3.) Reconnect the power cable
4.) Press and hold the OK button
5.) Momentarily press and release the power button while still pressing the OK button.
6.) When the display counts down to "0" and the power LED turns white, release the OK button.
7.) The radio should power up normally.
8.) Start SmartSDR.  Slice A will be on 20m (14.100)

Change to a different band.  Does SmartSDR still freeze and lose connection?