the error log now contains the following:

[Wed Feb 25 11:13:01 2009] [error] [client 127.0.0.1] Premature end of script headers: /usr/local/apache/cgi-bin/qmailadmin
[Wed Feb 25 13:05:11 2009] [notice] caught SIGTERM, shutting down
[Wed Feb 25 13:05:11 2009] [notice] Apache/1.3.37 (Unix) PHP/4.4.6 configured -- resuming normal operations
[Wed Feb 25 13:05:11 2009] [notice] Accept mutex: sysvsem (Default: sysvsem)
[Wed Feb 25 13:06:13 2009] [notice] SIGHUP received. Attempting to restart
[Wed Feb 25 13:06:13 2009] [notice] Apache/1.3.37 (Unix) PHP/4.4.6 configured -- resuming normal operations
[Wed Feb 25 13:06:13 2009] [notice] Accept mutex: sysvsem (Default: sysvsem)
[Wed Feb 25 13:14:35 2009] [notice] caught SIGTERM, shutting down
[Wed Feb 25 13:14:44 2009] [notice] Apache/1.3.37 (Unix) PHP/4.4.6 configured -- resuming normal operations
[Wed Feb 25 13:14:44 2009] [notice] Accept mutex: sysvsem (Default: sysvsem)


Please what else do i have to do for http://localhost/cgi-bin/qmailadmin to work

There is no error for the last 3 times you've restarted apache.
What happens when you go to http://localhost/cgi-bin/qmailadmin

When i go to http://localhost/cgi-bin/qmailadmin
i get this error message:


internal server error


The server encountered an internal error or misconfiguration and was unable to complete your request.

Please contact the server administrator, postmaster@gokahgh.com and inform them of the time the error occurred, and anything you might have done that may have caused the error.

More information about this error may be available in the server error log.

So it gives you the same error and it does not log anything in error_log?

this is what i get from tail /usr/local/apache/logs/error_log:

[Wed Feb 25 13:14:35 2009] [notice] caught SIGTERM, shutting down
[Wed Feb 25 13:14:44 2009] [notice] Apache/1.3.37 (Unix) PHP/4.4.6 configured -- resuming normal operations
[Wed Feb 25 13:14:44 2009] [notice] Accept mutex: sysvsem (Default: sysvsem)
qmailadmin: error while loading shared libraries: libmysqlclient.so.15: cannot open shared object file: No such file or directory
[Wed Feb 25 13:19:15 2009] [error] [client 127.0.0.1] Premature end of script headers: /usr/local/apache/cgi-bin/qmailadmin
qmailadmin: error while loading shared libraries: libmysqlclient.so.15: cannot open shared object file: No such file or directory
[Wed Feb 25 13:41:23 2009] [error] [client 127.0.0.1] Premature end of script headers: /usr/local/apache/cgi-bin/qmailadmin
[Wed Feb 25 14:02:30 2009] [warn] pid file /usr/local/apache/logs/httpd.pid overwritten -- Unclean shutdown of previous Apache run?
[Wed Feb 25 14:02:30 2009] [notice] Apache/1.3.37 (Unix) PHP/4.4.6 configured -- resuming normal operations
[Wed Feb 25 14:02:30 2009] [notice] Accept mutex: sysvsem (Default: sysvsem)

Let me understand this:
You have restarted apache at 14:02:30 and then hit http://localhost/cgi-bin/qmailadmin? Because if that's the case there is no error logged.
Anyway what is the output of:

The output of ls -l /usr/local/mysql-5.0.45-linux-i686-glibc23/lib/libmysqlclient*

is:


-rw-r----- 1 root mysql 2640104 Jul 4 2007 /usr/local/mysql-5.0.45-linux-i686-glibc23/lib/libmysqlclient.a
-rw-r----- 1 root mysql 2652068 Jul 4 2007 /usr/local/mysql-5.0.45-linux-i686-glibc23/lib/libmysqlclient_r.a
lrwxrwxrwx 1 root root 73 Feb 25 13:10 /usr/local/mysql-5.0.45-linux-i686-glibc23/lib/libmysqlclient_r.so -> /usr/local/mysql-5.0.45-linux-i686-glibc23/lib/libmysqlclient_r.so.15.0.0
lrwxrwxrwx 1 root root 26 Feb 25 13:14 /usr/local/mysql-5.0.45-linux-i686-glibc23/lib/libmysqlclient_r.so.15 -> libmysqlclient_r.so.15.0.0
-rw-r----- 1 root mysql 2239995 Jul 4 2007 /usr/local/mysql-5.0.45-linux-i686-glibc23/lib/libmysqlclient_r.so.15.0.0
-rw-r----- 1 root mysql 2226277 Jul 4 2007 /usr/local/mysql-5.0.45-linux-i686-glibc23/lib/libmysqlclient.so
lrwxrwxrwx 1 root root 71 Feb 25 13:10 /usr/local/mysql-5.0.45-linux-i686-glibc23/lib/libmysqlclient.so.15 -> /usr/local/mysql-5.0.45-linux-i686-glibc23/lib/libmysqlclient.so.15.0.0
-rw-r----- 1 root mysql 2226277 Jul 4 2007 /usr/local/mysql-5.0.45-linux-i686-glibc23/lib/libmysqlclient.so.15.0.0

This is wrong, it should be a symlink pointing to /usr/local/mysql-5.0.45-linux-i686-glibc23/lib/libmysqlclient.so.0.015. So run
to fix it.
Another think you should do is:
After that run again ldconfig, restart apache, hit the qmailadmin url and watch the logs.

This is what i get from the error_log:

[Wed Feb 25 13:41:23 2009] [error] [client 127.0.0.1] Premature end of script headers: /usr/local/apache/cgi-bin/qmailadmin
[Wed Feb 25 14:02:30 2009] [warn] pid file /usr/local/apache/logs/httpd.pid overwritten -- Unclean shutdown of previous Apache run?
[Wed Feb 25 14:02:30 2009] [notice] Apache/1.3.37 (Unix) PHP/4.4.6 configured -- resuming normal operations
[Wed Feb 25 14:02:30 2009] [notice] Accept mutex: sysvsem (Default: sysvsem)
[Wed Feb 25 14:58:35 2009] [notice] SIGHUP received. Attempting to restart
[Wed Feb 25 14:58:35 2009] [notice] Apache/1.3.37 (Unix) PHP/4.4.6 configured -- resuming normal operations
[Wed Feb 25 14:58:35 2009] [notice] Accept mutex: sysvsem (Default: sysvsem)
qmailadmin: error while loading shared libraries: libmysqlclient.so.15: cannot open shared object file: No such file or directory
[Wed Feb 25 14:59:04 2009] [error] [client 127.0.0.1] Premature end of script headers: /usr/local/apache/cgi-bin/qmailadmin
[Wed Feb 25 14:59:04 2009] [error] [client 127.0.0.1] File does not exist: /usr/local/apache/htdocs/favicon.ico

Thank you.

If you have done all of the above and still doesn't work, then chances are that the qmailadmin script looks elsewhere for the libraries. If it's a binary file, run:
to find out where it looks for the libraries.

I run

ldd /usr/local/apache/cgi-bin/qmailadmin|grep libmysqlclient

and this is what i get:

libmysqlclient.so.15 => /usr/local/mysql-5.0.45-linux-i686-glibc23/lib/libmysqlclient.so.15 (0x008da000)

A last attempt because I have to go.
Run

I did as you said but had the internal server error problem again.

I thank you very much for all the help you have given me so far. i have learn't a lot today.

I will have to reinstall mysql again from scratch. thank you.

There is no need to uninstall mysql, unless you want to install a more recent version, like 5.0.77 or 5.1.31.
The problem is with qmailadmin.
Reading the qmailadmin documentation it seems that it depends on ezmlm or ezmlm-idx, that in turn depends on mysql. According to your post you haven't install any of them.
So you have 2 options here:
1. You can use either the "--disable-ezmlm-mysql" when you run ./configure for qmailadmin to disable mysql support, or use "--enable-ezmlmdir=n" to disable ezmlm completely if you don't need it.

2. Install ezmlm-idx that is a bit tricky:
You need to edit sub_mysql/conf-sqlld and change the path to mysql in the 1st line prior running make. After installing ezmlm-idx you have to run make clean in qmailadmin and redo the qmailadmin installation.

IMHO you should use the 1st option and install qmailadmin without the ezmlm (or at least ezmlm-mysql) support.

Regards