Studiolive 16.0.2 Playback from DAW starts klicking after a few minutes.

The playback of my DAW (Protools) starts clicking and creating more latency after a few minutes. At the begiing all is normal it just starts after sometimes 3 minutes, sometimes 5 minutes. If I don't do anything on the computer for 10 Minutes, this phenomenon starts right at the begiing I'm starting the playback. Switching of and back on the asio4all driver solves the problem for a few minutes before it starts again. For testing, I have sent the DAW output signal to another interface at the same time, there I don't have this problem. So it must be the Mixer which is the problem....

Increasing the buffersize didn't solve the problem. I'm ruing everything on Win10.

Many thanks for any help.