We have encountered the same issue where authentication would fail with an error message of "Internal Error".
Cisco need to caveat this in the Installation document.
Is the error message from ACS failed authentication reports.
Is it affected for all users or only certain users.
Yeah the error message is on the ACS SE under failed authentication,
Unfortunately it effects all users from being authenticated.
The strange thing is you able to install the Remote agent on 64bit windows and synchronise it with ACS SE,you would have thought the remote agent would carry out a OS check during installation.
Thanks for the update, BTW what version do you test?
Does the server need to be rebooted after the installation?
we tested with v4.2 and unfortunately the DC's that we installed the remote agent had to be rebooted. In all honesty we did not try using the remote agent before rebooting, as we followed the installation guide.
We didn't test ACS applications and remote agent on 64 bit servers. Therefore this platform is not supported as of now.