Using NX Server Manager in conjunction with the threaded version of Apache 2 (apache2-mpm-worker)  as the Web Server on a 32-bit Linux O.S.  can cause problems with the login to NX Server.

It has been verified that in such a scenario the user can login to the NX Server Manager Web interface as well as to NX Server. Nevertheless, when the user tries to access any of the interfaces to manage the server, he/she is immediately prompted with the logon screen again.

This problem doesn't occur if the threaded version of Apache 2  MPM  is installed on a Linux 64-bit.

More information about the apache2-mpm-worker are available on the Apache official Web Site: http://httpd.apache.org/docs/2.2/mod/worker.html

This Multi-Processing Module (MPM) implements a hybrid multi-process

multi-threaded server. By using threads to serve requests, it is able

to serve a large number of requests with fewer system resources than

a process-based server. However, it retains much of the stability of

a process-based server by keeping multiple processes available,

each with many threads.

In order to solve possible issues on Linux 32-bit, it is suggested to install the apache2-mpm-prefork  version of Apache 2, i.e. a non-threaded Apache server, instead of apache2-mpm-worker.

You can refer to the Apache Web site for more details:  http://httpd.apache.org/docs/2.2/mod/prefork.html

This Multi-Processing Module (MPM) implements a non-threaded, pre-forking

web server that handles requests in a manner similar to Apache 1.3. It is

 appropriate for sites that need to avoid threading for compatibility with

 non-thread-safe libraries. It is also the best MPM for isolating each

 request, so that a problem with a single request will not affect any other.