We have users from another corporate entity on our site who we provide with internet access in order for them to access the Outlook Web Access server at their employers site. While we were running Proxy 2.0 they had no trouble doing this, but since upgrading to ISA2000 they have had no end of trouble with the system. The third party site insists that this is our problem, not theirs.
On Proxy 2.0 users were only asked for username and password when accessing the OWA server - now we have moved to ISA server they are additionally asked for the domain, and they are asked to input their credentials multiple times.
In the short term I have implemented a work-around by adding the remote site to the 'Local addresses' list in IE and piping their traffic through the firewall client instead (The ISA Server is not configured to redirect http traffic from the firewall service to the web proxy service) - this allows them to log in and use their e-mail, the credentials they need to enter depend on which browser version they are using - IE5.5 users do not need to put in the domain, whereas IE6 users do.
Another observation I have is that this problem does not occur at all on my machine, which is running WinXP and IE6 - the users either have 98 or 2000.
I have allocated such a high point value as the users of the system are beginning to complain both to my department head and to the IT head at their organisation, so I need either a solution we can implement, or a solution I can tell the third party to implement.
Please feel free to ask for more info - there is a high probability I have left some out here.