DDJ-SZ Dropout Serato 1.92

Hi. Sorry for my bad english :-)

I have a Problem with the DDj SZ in use with Serato Dj.

Setup: Serato DJ 1,92, DDJ SZ FW 1.20 
Win 8.1 Intel core i3 4gb Ram.

I was playing my set on a wedding on Saturday.

I started with a playlist in Auto Dj mode, for the time, all people are incoming and eating etc and everything was ok.

As the party started, I played 4-5 songs and suddenly stopped the song.
I was totally shocked and it was very embarrassing.
I turned off the ddj sz and again immediately.
was as the sz booted and has recognized serato played the song normally.

Then for a long while happened nothing. I still switch the latency to 10ms and the usb port plugged in b to be sure that it wasn´t the problem.

The CPU utilization was not very high. and serato itself is not frozen, otherwise I would have to start the new.

But eventually, it happened again. a total of 3 times in the evening.
Now I would like to know how I can counteract this.
Is there a communication problem?

Is it a USB cable?
I do not get it. something must not happen, yes.
Can it be due to the new Serato version?

I hope you can help me.

Best regards

Denis