Huh, I just had to do the ReCaptcha two or three times thus far, "Suspicious Activity Detected".
Ok, my style for browsing these forums, is to just browse the main header thread and sub-forum header pages, and then "Open in new tab" for each thread. So I end up, over a span of possibly a week or two, with HUNDREDS of AT forum tabs. (Thankfully, I have a powerful desktop rig.)
Anyways, I recently had reason to re-boot (GPU issue), so then I had to re-login, and then I set about closing those extra tabs, which, of course, loads the tab, then closes it. I can click them about one per second or slightly faster, so possibly that's why I got flagged.
Posting this thread, I keep getting "security" pop-ups. Let me clear my cookies.