Unable to login as super user immediately following install

Hi, I have just finished installing Piwik, however, when I try to log in as the super user I get a pink box with the message:

Error: Form security failed. Please reload the form and check that your cookies are enabled. If you use a proxy server, you must configure Piwik to accept the proxy header that forwards the Host header. Also, check that your Referrer header is sent correctly.

I am 100% positive that I am typing in the password correctly. Any attempts to reset the password through the “Lost your password?” link result in “HTTP Error” where it previously said “Enter a new password for your account.” Directly modifying the password’s hash/salt in the config/config.ini.php file does not change anything.

I am running Apache 2.4.6 with PHP 5.4.20 and MariaDB 5.5.33; all modules requested during the install are provided.

When you get a HTTP error, check your server error log for the actual error message ?