My b2evolution Version: Not Entered

I have installed b2evo v 0.9.1 as directed. When I log in, it accepts my password, but any time I click a link or a button the session prompts me to log in again (session not being created maybe?). The behavior is exactly the same whether I'm using firefox 2.0.0.3 or IE 6. I have specifically allowed cookies for this site, and they are being created. Any idea what's wrong?