Have you tried tail /path/to/apache/error/log in your shell?
Most generally, "blank page syndrome" is a combination of some error, and the php.ini settings for error_reporting().
However, there are two kinda weird things here. One, it's kind of hard to see how you might screw up a call to phpinfo(), and two, I don't usually note that PHP sends up the DOCTYPE declaration for "blank" error pages.
Do you own the box?