Video Export not working

[aeiou112358]

When I'm trying to export a video-file the progress bar just freezes. Not sure why that's happening. It's been for a while, since several updates. LR should be on the newest version.

Is it possible that this is a video-codec-problem (shall I try re-installing them)?

I think it has nothing to do with RAM, CPU-Speed or harddrive-space (MacBook Pro Late 2013, 2.8GHz, 16GB Ram / 4TB free space on external Drobo 5D Raid-System, 320GB on main harddrive).

Any ideas?

[aeiou112358]

Update: it's not the video-codecs... downloaded "Pro Video Formats 2.0.6" from Apple website, but nothing is happening on export (progress bar freezes) ... zero, nada, zilch...

Any suggestions?