problem with about:blank

My (swt+java+mozilla) is able to run, and if I navigate to http sites 
such as http://www.google.com, it can show the page correctly. But when 
I try to navigate to "about:blank", I got a windows native access 
violation exception. Is there anything special with "about:blank".

Another problem is that when I don't have internet connection, I will 
not be able to connect to http://www.google.com, then if I use mouse to 
click the client area, I will also receive a windows native access 
violation exception. This also happen to the mozilla official mfcembed 
program, but not to the mozilla browser itself. Any one know why?

Thanks.

jml