Error when python script run as cgi script

[sophie_newbie]

Hi, I'm running a python script which if I run from the command line
as root runs fine. But if I run it through the web-browser as a cgi
script gives the following error "Error in X11: unable to start device
PNG".

Now I should say that this python script is calling fucntions in R (a
scripting languange used in statistics) using the python module RPy,
so this I dunno if this is entirely a Python question, because as far
as I can see the error is being thrown by R. But then as I say, when
the script is run by the root user from the command line everything
goes off without a hitch.

So I dunno is there some way to run a CGI script as root, maybe thats
a bad idea because of security? But any ideas would be welcome.

-Thanks.