Krpano testserver not running on OSX 10.9

I need to test a lot of settings locally but can't get the test server to work on my Macbook with the latest OS.
Whenever I open a folder or drag a file onto it, the application crashes.
An ideas?

Thank you
Jürgen

Thank you Klaus.
I thought there should be no other application be interfering with the Testserver.
However, your hint made me suspicious and I first tried another port, but the app still crashed.
I then tried to stop everything that I thought might be related to anything with web and remote access and after that the Testserver suddenly worked.
Funny enough that it seems to be still starting properly after I restarted the other apps.
Will observe the issue and report if it reappears.