.htaccess in wp-admin – what about the subscribers?

I’m intent on protecting my wp-admin folder from outsiders by placing an htaccess file in /wp-admin. I’d like it so that access to that folder is specific only to the list of IP addresses I’m allowing.

Code I’m using (assuming that is my IP):
order deny,allow
deny from all
allow from 123.456.789

Problem:
This works great except for one problem. What about regular users that are signing up to be able to participate/comment on the blog (i.e. subscribers). They too are being blocked when they try to edit their profile or login.

Is this normal? Am I doing something wrong? Is there another way to accomplish this?

Again, my goal is to protect my main admin panel.

ERROR I’M GETTING as a subscriber when I try to login or change my profile:

Internal Server Error
The server encountered an internal error or misconfiguration and was unable to complete your request.

Thanks!