If the name of the sound device is not in English letters, then the program crashes when you try to ‘stream’ an audio device.
Steps to reproduce
This has been reported by a user using a Cyrillic alphabet. The crash occurred when selecting an Audio output node, selecting a Source device with a non-English name and then clicking on the Streaming checkbox.
It’s possible this happens at other places in Lightact where non-English characters might appear.
Open Windows Registry Editor and do a search for the name of your audio device. You can then change the name to one using only English characters.