hello..i have install Ourmon(network monitoring tool) manually on my FC8 and seem to be ok.but then i started to get message in my /var/spool/mail/root.

how do i stop this message from coming?what happen?

This is the first clue:

From: root@localhost.localdomain (Cron Daemon)
To: root@localhost.localdomain
Subject: Cron <root@localhost> /home/mrourmon/bin/omupdate.sh

Your cron job /home/mrourmon/bin/omupdate.sh is failing. Its failing because

cp: cannot stat `/home/mrourmon/tmp/mon.lite': No such file or directory
Can't locate RRDs.pm in @INC (@INC contains: /usr/local/rrdtool-1.0.49/lib/perl ../lib/perl etc

and
at /home/mrourmon/bin/omupdate.pl line 42.
BEGIN failed--compilation aborted at /home/mrourmon/bin/omupdate.pl line 42.

etc

Basically you need to read the shell source and make sure the files it expects are where they should be.
You need to use the CPAN tool to install RRDs.pm (at least). The Perl prog needs this and other files.

To install from CPAN, login as root and

perl -e shell -M CPAN
cpan> install RRDs

To check a perl prog for syntax without running it, try

perl -wc file.pl

There should be some docs for this stuff that specify what you need to setup to make it run.