FCD Windows hangs

Hi All, Today I tried reinstalling the script again, it has worked before but I've changed PC's. Upon running the fcdp-tetra_demod_fft.py file the spectrum windows opens normally but after a few seconds the spectrum line stops moving. Do you guys have any idea what is causing this? I have tried reinstalling everything, gnuradio, libtools and even Ubuntu... But no success..:( Thanks! -Pepijn