[Obsidian Dragon]

Per Darryl Ramm, "You should also always suspect plugins that loaded immediately prior to the one that appears to cause failures like this."

I suggest moving all 3rd party plugins to the unused folder, delete prefs, and relaunch Protools. If it lunches fine, start moving plugin back one at a time (or in small batches) and relaunch until you find the offending plugin. Move that problematic plugin back out to the unused folder and continue testing the rest of your plugins.