that's likely the result of google scholar blocking you as a presumed bot. Have you tried doing another google scholar search? Do you get some type of error message from google?

you can try clearing cookies (or at least google scholar cookies). Good chance that will help.

no. I don't think we've ever seen a hard lock-out such as this where neither filling out the captcha (if you get one) nor clearing cookies helps. Clearly, google doesn't want you to be doing whatever you're doing and even if Zotero could do something about that--which it may not be able to anyway--it probably shouldn't.

I'm not saying google is right--but it's their service, so it's their rules and this is what they have to say about this:
http://scholar.google.com/intl/en-US/scholar/help.html#export

edit: fixed link

sorry, link fixed.

See https://www.zotero.org/support/getting_stuff_into_your_library#large-scale_imports_from_databases for a workaround

There is no "fix" per se for the issue as it's simply a google policy.