Glad you got it sorted out Mike.
 
 
I know I'm way late to the party here but I just want to add that there is a forum on N I's site that many don't know about, for questions, user-based support, etc.
 
Also, like Baps, I have both K4 & K5 running together, [but I do not have Komplete].
 
I've have used both the on-line & off-line Service Center versions and again no troubles - both K4 & K5 appear for activation.
 
The last update for K4 was 4.2.4. 

Thanks. I spent some time over there.
 
The problem I was having was that instead of finding any information that explains that Service Center will not let you have a K4 and K5 library tab "library" with the same name I found a ridiculous amount of bad and erroneous advice... most of which seemed to repeat an erroneous official solution offered in Native Instruments knowledge base. 
 
Here's what I have figured out: If you have a library that is licensed for K5 then any K4 libraries with the very same name will not open with commands made in the Library tab of Kontakt 4.
 
As long as I use the Database or the File tab in Kontakt 4 then I still have complete access to all the Kontakt 4 libraries and every thing works great.
 
I was amazed that all the posts I saw about this ended with people being pummeled into believing they had made some sort of mistake and butchered their K4 library install by overwriting it with K5 stuff. No one bothered to post the actual answer that it is just a limitation of the Service Center licensing.
 
It was sort of frustrating.