Ubuntu freezing

I’ve just started using Ubuntu and installed Kodi following the command line instructions in the wiki. This installed Krypton rather than Jarvis, which I assume is intended (I also found that software centre is installing Krypton beta 3 too).

Anyway, I find using Krypton is very stable, both in Estuary and Transparency, however as soon as I alt-tab to any other program I can’t get Kodi to work again, either by alt-tabbing back to it or clicking its icon in the task bar. I don’t think Kodi is locking up as the log kept updating while I was scanning music to my library, it’s just the display is completely locked and I can neither activate it with mouse or keyboard. If I choose quit by right clicking the taskbar icon nothing happens, and the only way I seem to be able to close it is by killing the kodi.bin process system monitor. The kodi icon stays open in the task bar but if I close and re-open system monitor it will shut down.

Is this known behaviour, or is there something I’m missing in using Ubuntu?

Thanks

debug log – in this debug log all I’ve done is open kodi, use up and down arrows to go up and down the menu, alt-tab to the desktop, alt-tab back to kodi and it’s locked up.