Browser freezes on login page of provider

[mario]

Hi,

we're running WinGate 6.04 on a MS Windows 2003 Server, using a dial-up connection.
WinGate runs as a cascading proxy with an external proxy.

The problem:
Browsing in internet generally gives no problems.
Except for the following case:

When a user tries to read his email on the providers site, e.g. hotmail, he just arrives to insert username and password, but then the browser remains blocked/freezed. The following page (the one with the user-menu or emails) does not appear. This happens for all providers.
It happens in the same manner trying from server or from workstations running Windows 2000 Professional or Windows Xp Professional.

For now, we've tried to disable the cache, eliminated the folder wingate\cache, set the parameter "number of days before rechecking HTML files" to '0', without obtaining positive results. I.e., the browser still remains blocked on the 'login page' or after the 'login page' of the providers site.

Is there something else we can do to solve this problem?

Thanks

Mario