MR Tech Toolkit
Zotero has troubles with the collections windows when MR Tech Toolkit is activated.
This is an old discussion that has not been active in a long time. Instead of commenting here, you should start a new discussion. If you think the content of this discussion is still relevant, you can link to it from your new discussion.
Are you sure it is the Toolkit that is causing your issue? Can you try disabling any other extensions and see if that resolves the issue? If your problem persists strictly with MR Tech Toolkit please describe exactly what is going wrong and use the report errors button to submit an error report. Then post the report ID here in this thread so we can take a look.