time out issues when connecting to DTDs

I'm using saxon 6.5.3 and docbook-website. I'm having a hard time
"compiling" any xml. 

I get the following error:
"Error reported by XML parser: Cannot read from
http://docbook.sourceforge.net/etc..... Connection timed out:connect)" This
occurs for the autolayout and targetset DTDs

I can get to the DTD by opening my internet browser, so I'm wondering if it
has anythign to do with the proxy we have setup here at our company.

Is there any particular protocol/port that should be open in order for me to
be able to do this?  Right now I've been replaceing the URL with a local
path, (as I haven't figured out the cataglog out yet)

Thanks!

LN