I had this problem myself when I purchased and installed the ARS3 plugin. I have no need and no intention of using the NX Head Tracker and was starting to really get annoyed with the plugin popping up every time.
For Mac users, the plugin can be located here: Macintosh HD/Applications/Waves/Plugins V11/WavesHeadTracker
Just rename the WavesHeadTracker plugin to WavesHeadTrackerOff, that will solve the problem. Big thanks to Matthew Sorrels for sharing this workaround!