Login problem

If I try to protect my /wp-admin dir by .htaccess or allowing only from my ip, registered members receive a FORBIDDEN when trying to login. I was told by my host that the page is calling a css file. Is there a way to get around this, allowing members but still protecting my /wp-admin.

PS: Yes I have used the password protect dir in my cpanel, this brings up the protected dir screen for members as well.
Please help.