[MashaT]

I used to have Glo HD and it had similar type of issue, when reading for a long time, and/or jumping back and forth thru chapters, Kobo device would freeze on a page.
On Glo HD it was solvable without restart, it wasn't a total freeze of the device, more like unresponsiveness of touch screen, if I were to press a power button, the device would go to sleep and after 10 or so minutes when activated again it would be unfrozen. Sometimes I did have to restart.
On Libra 2, the freeze is more total, neither touch screen nor any of the buttons work. Leaving device (while closing sleep cover) does nothing other than wasting batteries since device remains on at same screen light adjustment when it went frozen regardless of room light. Short of restart nothing works.
It does seem to be more frequent with more recent books, which are more HQ and are larger in size.