Hi there
I don’t know too much about RSS feeds but I know a great deal about .htaccess and what is in there should not be played with too much if you don’t know what you are doing.
Your webhost or even your webhosting control panel may have written to the access file for things like url mod rewrite, error page redirects or even old url redirects.
Check here for the answer and then be sure to check with your webhosting provider before attempting to access and change your htaccess file.
Some hosts do not allow customers to change the .htaccess file.
Clint