What's wrong with my router

I can't connect to my router's admin interface. It times out. I'm using Firefox 3.0.11.
In the windows command prompt if I ping the address for my router, I get no strange behavior.
How do I connect to my router? What am I doing wrong?

Sometimes I can access the admin interface but it is very slow and often times out.

some routers only allow you to get to the admin page only if you are using ethernet, not wireless