On the latest version of WordPress.
When trying to login in via mysite.com/wp-login.php, the screen goes blank and only the word "error" appears in the upper left-hand corner.
A few minutes later, I was able to login. So I went to edit a post. Clicked "edit" and again... screen goes blank.... one word "error" message. Luckily, the front-end of the site is still working fine.
I pulled the wp-login.php file from another one of my sites to compare on my laptop. Went through all 738 lines... all the same. So I'm fairly certain the wp-login.php file is not corrupt.
This happened at a random time. I was tinkering with WP's commenting settings while trying to get Disqus to display comments. In other words, I wasn't messing around with any .php files or even the FTP server. Just common WP settings.
Any clue why I'm getting this one word "error" message? Or does anyone know where I should start?