So heres the deal.  You have clients behind ISA 2004, trying to browse to a redirecting website.  The site starts with an http connection, the user is prompted to logon, or the site redirects to a more secure connection <https>.  The interesting thing is that it worked BEFORE installing ISA 2004 Service Pack 2.    Hmmmmmmm.

When trying to connect to the https portion of the site various errors are returned:

• 400 bad request.
• 11001: host not found.
• http://%20 example .comom

Why is this happening?

It appears the problem is caused because ISA will add spaces between some headers and their values.  If this happens some webservers see the space as the beginning of the hostname.  The server then redirects the browser to a website that begins with a space that fails.  The browser then fails because it cannot access the malformed URL.

How do I fix this? 

1. Open ISA Server Management
2. Configuration
3. Add-Ins
4. Web Filters
5. Properties of the "Compression filter" - Uncheck "Enable this filter"
6. Properties of the "Caching compressed content filter"  -  Uncheck "Enable this filter"
7. Select Apply at the top of the screen to apply the changes.

>edwalt