buddypress plugin

hello there everyone,

I just installed buddypress social networking plugin on my site. I also changed my theme from wordpress twentyeleven theme to buddypress-compatible theme, namely buddypress default theme, and everything seems to be working fine. except for the top admin-bar over the header image. there are three links on the on the bar: “log in”, “sign up”, and “visit”. all the links are working except the “log in” link. if i click on it, what i get is the “404 page”. i dont what could be wrong as i am still new to the wordpress software. can somebody please help.

thank you