WordPress MU

After I install Wordpress Mu under there, I can not see anything but the following information:

Internal Server Error
The server encountered an internal error or misconfiguration and was unable to complete your request.
Please contact the server administrator, [no address given] and inform them of the time the error occurred, and anything you might have done that may have caused the error.

here is it installed:
http://www.cabi.net.cn/blog

Thanks for your help.