Route adds ?admin.html to the end of my URL

I keep all of my admin controllers in /admin, and I want
http://domain.com/admin to route to :controller => admin/login, and
:action => login.

I added map.connect ‘/admin’, :controller => ‘admin/login’, :action =>
‘login’ to my routes, and it works great.

However, when I go to http://domain.com/admin the URL is changed to:
http://domain.com/admin/?admin.html

I have no idea what might cause this! Has anyone seen this before?