You should disable all the plugins and restart Zotero to see if the problem goes away.
If you can access the menus, restart in Troubleshooting Mode (Help → "Restart in Troubleshooting Mode…") and disable the plugin. Otherwise, you can hold down Option (Mac) or Shift (Windows) at startup to enter Troubleshooting Mode.
If Zotero works properly again with all plugins disabled, you should identify which one is responsible for the problem, and report to the plugin developer.
If you can access the menus, restart in Troubleshooting Mode (Help → "Restart in Troubleshooting Mode…") and disable the plugin. Otherwise, you can hold down Option (Mac) or Shift (Windows) at startup to enter Troubleshooting Mode.
If Zotero works properly again with all plugins disabled, you should identify which one is responsible for the problem, and report to the plugin developer.