Yesterday with the before-last-patch at the time of writing, I had the levelcache message exactly once. Wasn't able to reproduce later.
If I recall correctly, what I did was:
1. delete all savegames I had (not really playing the story for now, so I can do that
)
2. try to save
3. get warning
4. retry saving
5. game freezes, music keeps playing (wasn't able to reproduce)
6. kill the process via task manager
7. restart the game
8. saving games worked for the rest of the evening
)
