There are web statistics gathering solutions such as webalizer you might want to look at.

Generally - when I get a premature end of headers or malformed headers error I have a bug in my script.

You can run scripts from the command line to see what it returns and debug there first.

You could also use telnet on port 80, request one of your pages and see what the response is from that. Maybe you are using this technique already.

I imagine this exec call is simply incrementing numbers to some file(s) or DB table(s) and that you have some other script which reads the data back.

From the exec documentation, if you are using -w or use warnings; and use an exec without a following die, warn or exit then Perl will complain.

Check the permissions and accessibility of the program being exec'd and consider using the system call.

Also consider using use CGI::Carp qw(fatalsToBrowser); to help debug what's happening.

Let us know how you get on.