Problem with Endian Proxy and Google Earth

Hello,

we have a problem with Endian Community Version 2.5.1 an Google Earth.
We use local Authentication (NCSA).

We are able to download and install Google Earth. Browsing is also
possible. If I want to login with a Google account I don't get a login
page. It appears to be a certificate problem although https isn't
blocked and the following Google servers are whitelisted:
google.com
kh.google.com
maps.google.com
geo.keyhole.com
auth.keyhole.com
geoauth.google.com

Also the search feature isn't working on every client. We made tests on
Windows XP and Windows 7. On Windows XP search isn't working, on Windows
7 at least sometimes.

This problem only occurs with NCSA authentication. If it's turned off
Google Earth works without problems.

We tested this on a second machine running EFW 2.5.1 and had the same
problems.
It's important to know that a client which was already connected to
Google Earth without NCSA authentication will have no problems with
Google Earth and NCSA authentication turned on.
But I don't know if this works fine for a day or for a month, yet.