IntelliJ always errors when loading Scala facet

The last couple of weeks every time I opened my project with IntelliJ I would get an error with the Scala plugin and the system would become unusable while indexing all the time.

I considered switching from my usual stack Struts 2/Spring/Hibernate to Lift/JPA and Eclipse but after I invalidated the cache (File -> Invalidate Caches) it seems to work again.