fzurell

I was able to work around this problem by using the Developer Mode in Firefox. I noticed that two JS files couldn’t be download from the Security Plugin folder. The files do exist, but the URLs were appended with caching information.
I used the “Edit & Resend” function of the Firefox Developer tools to strip off the caching arguments from the actual file name. That seemed to have put those files in the browser cache. After reloading the login page then, the “i’m a human” checkbox was displayed again and I was able to login and deactivate this function….

I found the problem in the Apache mod_memcache/mod_diskcache problem.

It was working fine on my development machine with the very same wordpress files but the apache missing the cache modules. So I deactivated them on the live system too. This fixed the problem…

Thanks for the suggestions.