I'm evaluating this brilliant looking app and encountered something which appears to me a bug for it breaks all the user experience apart. When playing my composition which consists of only two audio file placed on two separate audio tracks. When playing the project, at first, everything sounds great but when time indicator reaches about 85% on the timeline, suddenly it snaps at the end of the project and abruptly ending the project.
I'm afraid that without a concrete minimal example to reproduce we cannot help nor fix a potential bug.
It seems that this report is related to a very old unmaintained version. A lot changed since then and it is likely that this has been fixed. Feel free to reopen this bug or create a new report if this is still happening with the latest version (https://kdenlive.org/en/download/)