Thanks for the response. I use Kontakt 7 quite a bit. I did a test.
Rackspaces without Kontakt 7 - replace mixer plugins fine.
Rackspaces with Kontakt 7 with 2 or less stereo outputs from Kontakt - replace mixer plugins fine.
However, rackspaces with Kontakt 7 with 3 or more stereo outputs from Kontakt - crash every time.
This must be a Kontakt 7 issue?
Thanks again.