Do you mean EM CS5.5 crashed the first time when you were installing NKS5 plugin and after that crashes every time when launching? Please open Finder, hold down "option" key, click menu "Go"->"Library" to go into hidden Library folder, then go to its subfolder "Application Support/Adobe/Extension Manager CS5.5/Configuration/Extensions". Check if files NKS5.mxi, NKS5.mxi_air and NKS5.zxp exist here and delete them.
Yes, the EM CS5.5 crashed the first time while attempting to install the NKS5 plugin. Every time after that when I tried to open the EM CS5.5 app it crashed.
I checked the Extensions folder as you suggested below and found it empty/
Any other thoughts?
Currently I have no CS5.5 installed in my Mac. I tried it on Windows. The location is "C:\Users\Public\Roaming\Adobe\Extension Manager". I guess it should be "/Library/Application Support/Adobe/Extension Manager" on Mac. If you can't find them in this folder, you could search your whole Mac drive.
I found the location with no problem, there is no NKS5 in there. I believe the problem lies with the 5.5 Extensions manager. Should I uninstall the 5.5 Extensions manager and reinstall it?
That's fine. It's the quickest way to solve the problem.