ISA Server 2006 Publishing Issue with MOSS 2007
"Troubleshooting Sharepoint/MOSS 2007 publishing through ISA Server can be really challenging, mainly because most of the times the argument is: but it works just fine internally. Although this can be a good argument it doesn’t prove that the issue is on ISA Sever. .."
Check it out the complete post that born from a nice collaboration between ISA and Sharepoint Team: