I'm using Better WP Security from months without any problem but this morning I've found a website giving error 500 because
.htaccess: deny requires at least two arguments, 'from' followed by hostnames or IP-address wildcards
effectivelly I've found a 'deny from' followed by nothing in .htaccess, and just removing it solved the problem.
can't understand how it happened, do you check for non empty values when writing to .htaccess?
I'll let you know if this happens again.
Thanks for your usefull plugin, anyway.
All the best