Authentication problem with INTERNET EXPLORER 6

[itgmorigia]

I set a wingate server for authentication only (the machine has only one nick) however the proxy HTTP service often denials pages downloading at random:
The server listen on port 8080, the users name are assumed correctly as seen in Gatekeeper message logs but the page is blocked with authentication failed. The failure appears at randomly for more than one machine (the username used is the same for more than one client).
Is it possible that a session for the same user that uses more than one PC may be confused by the server?
I use Intercept on the HTTP service.
The users are authenticate by AD groups. The wingate server is a member server, not a domain controller.
The policy is accepted only if users are authenticated. Default policy must also granted.
This is a big problem for me because a page that seems to browse correctly it may be not shown if reloaded.
Another question:
Why is not possible to use nested groups for authentication in wingate?
I noticed if a user belongs to a AD global group named FIRST wich is nested to another global group named SECOND and the SECOND group is assigned in an authentication policy in wingate, the users is not authenticated.

Thanks.
Davide Cottignoli.
Istituto Geometri "C.Morigia" Ravenna Italy

[itgmorigia]

I omitted some information:
The IE client uses proxy settings for port 8080 for all protocols.
The wingate server does not have NAT enable.
There are no authentication problems if uses WGIC.
It seems there are no problems if the users is an administratorfor the client PC.
The users that do not randomly pass the authentication are students which have some limitations on the clients machine but even with users that have more rights (but not administrators) on client machine are sometimes blocked.
The clients are XP Pro NT4 and 2KPro.

Thanks for help in advance.

[itgmorigia]

I noticed that after resolve the "various computer names in logs" issue (see the topic "Various ComputerName logs" which concern a DNS problem), the problems with Internet Explorer has disappeared, however now I experience the same problem described in "Images not showing in IE on some computers".

Is it possible that the DNS order problem in wingate server does not permit the corrected authentication of users by Active Directory whose database is installed on another machine?
The manual DNS settings in Wingate were in the following order:
The external proxy router: 192.168.1.254
The internal DNS domain controller: 192.168.1.3

Davide Cottignoli