Hi Mike,
After updating Bad Behavior plugin by Michael Hampton to v2.1.14 or v2.1.15 (from version 2.0.44), I can no longer access my blog (nor can people comment). When I enter the captcha to login, upon submitting it, I get the error:
"ERROR: Could not read CAPTCHA cookie. Make sure you have cookies enabled and not blocking in your web browser settings. Or another plugin is conflicting. See plugin FAQ."
It isn't a cookie problem, as it fails on any browser I try (or even on a different computer). Disabling Bad Behavior or reverting to the older version allows it to work properly again. I notified Michael, but wanted to make you aware of it as well, as I don't know where the problem is. As long as I stay on Bad Behavior v 2.0.44, everything works great, but I'm hoping to stay current on my plugins. Thanks.
http://wordpress.org/extend/plugins/si-captcha-for-wordpress/