The title says it all. My Waves plugins are available in a session. I use them, save the song. Try to load the song and get a message about can't load the plugin (H-Comp) and again, can't load the plugin (Studio Rack). They worked when I saved but won't load. I'm not a big fan of do-overs, particularly when, at the moment, it's an exercise in futility.
Any ideas?