BuddyPress.org

I wanted to create a portal for alumni of my school and I selected Buddypress for the purpose. For that purpose, I installed WordPress 3.0.1 on a subdomain something.school.edu
Then, I installed Buddypress.And, it installed without any hassle.
When I open something.school.edu everything looks fine but when I click on any link there like “Activity”, “Members”, “Groups” or anything else other than the posts and comments, 404 error(The requested URL /groups/ was not found on this server.) is displayed. Further, when someone tries to register, then too, it shows the same error.
So, in a nutshell, nothing works except the front display.
So, what should be done to make it work?
I think I’ve installed it in incorrect manner but I just followed the instruction. And, I’ve tried automated as well as manual installation but the same problem persists.

Any help will be really appreciated!