Network Login Failed for ISA with SharePoint SSL

Setup:

ISA 2006 on a Windows 2003 SP2 - NOT tied to the domain
SharePoint Server with multiple extranet sites
Wildcard SSL Certificate issue from Network Solutions

I currently have about 10 SharePoint Portals. Each has an Extranet so we can view the site from the outside world. I recently obtained a Wildcard Cert from Network Solutions. I've bound the certificate to one of the Extranet sites by using the following command:

cscript.exe adsutil.vbs set /w3svc/<site identifier>/SecureBindings ":443:<host header>"

I can see that 443 is bound to that Extranet site.

Incoming traffic gets routed through our ISA 2006 server. I've created a web publishing rule and created a listener for this extranet site. When creating the rule and listener, I followed the following article :

http://technet.microsoft.com/en-us/library/bb794854.aspx#SecureWebPublishing

The SSL Wildcard certificate has been installed on the ISA server and is bound to the external NIC of the ISA server.

Every time I try from home to goto "https://portal.mysite.com" I'm told in IE that the page isn't able to be displayed. I then look in the Monitoring -> Alert section of ISA and find the following:

Description: ISA Server was unable to establish an SSL connection with portal.mysite.com. The network logon failed.

 The failure is due to error: The network logon failed.

Can anyone help in figuring out what is causing ISA to report this error?!?!?!