Your issue is most likely not the same then the issue that the first poster ahs as every problem that occurs during installation results in this error message, so plaese make a new thread the next time.
To your problem, I guess you use a Centos4.x version? then try this:
We also need the module HTML::Parser. We could install the CentOS package perl-HTML-Parser, but this version is too old for the SpamAssassin version that comes with ISPConfig. It would result in the following error message during ISPConfig installation:
REQUIRED module out of date: HTML::Parser
Therefore we must install the latest HTML::Parser using the Perl shell.
Run the following command to start the Perl shell:
perl -MCPAN -e shell
If you run the Perl shell for the first time you will be asked some questions. In most cases the default answers are ok. Because there's no ncftp package for CentOS, the Perl shell cannot find the programs ncftpget and ncftp, and you'll see something like this:
Warning: ncftpget not found in PATH
Where is your ncftpget program? 
Warning: ncftp not found in PATH
Where is your ncftp program? 
It's ok to hit ENTER in both cases.
Please note: If you run a firewall on your system you might have to turn it off while working on the Perl shell in order for the Perl shell to be able to fetch the needed modules without a big delay. You can switch it on afterwards.
Now type in the following command to install the Perl module HTML::Parser:
If the installation is successful, you'll see a line like this at the end:
/usr/bin/make install -- OK
afterwards to leave the Perl shell.