For those who have ever had troubles with error 500 due to their .htaccess file and after uploading a correct version coped with the same situation
, there is the solution:
Do NOT use UTF-8/unicode encoding in your .htaccess! (if you are users of Notepad in Windows, simply use its default ANSI)
I see it is not problem for experts, but as I read some threads, there were some people who had absolutely the same problem; may it be helpful to them.