virtualbox.org

I recently installed VBox 3.0.8 on Windows 7, then proceeded to install CentOS 5.3 64bits as a guest OS. The CentOS installation went smoothly, but when trying to boot it after the install, I get only a black screen. Even though the VM is configured to use a single processor, I see it using anywhere between 5% and 30% of all 4 cores on my i7, so it seems like it's trying to do something behind the black screen. I tried letting it run for over an hour, still nothing beyond this black screen.

Anyone else experienced this on similar setup ?
Thanks in advance for any help.