I get the following when trying to run the png command or save image:

        error writing "testing.png"! Please check directory...

This is irrespective of user/directory, so I don't think permissions are the problem.

I think perhaps the most important problem is that we are trying to understand the  fundamental workings of the universe via a language devised for telling one another when the best fruit is.

        -- Terry Pratchett, alt.fan.pratchett

Gordon Wells
Bioinformatics and Computational Biology Unit
Department of Biochemistry
University of Pretoria