I just upgraded to Kontakt 4 today.  Whenever I try to play something, it comes out fine.  That is, excluding all marimbas and snares.  The volume on those were inaudible (unless I turned the aux sends up all the way and turned up my mains).  Kontakt how no trouble recognizing that the samples are there (i.e. cpu recognition).  And the last confusing piece is that Kontakt 2 worked fine. 
Any thoughts?
Thank you!

Are you using the VDL 2.5.2 update?