Interesting.
I have KOMPLETE 9 working away with platinum no problem ..
I left KOMPLETE installed on my system. Uninistalled X3, cleared remnants of same from registry etc ... Installed Platinum, set the VST folders and it found everything.
I will admit I have not tried everything in Komplete yet BUT in the main using Kontakt and Massive.
OK a caveat - I do notice that any project with Kontakt can take quiet a while to load. Im not sure if thats a "bug"?