As I've written before, I couldn't preview some kind of files and downloading them neither (not just some extensions but all). I don't really know if it's a real bug or not but i've saw other people whith the same problem. To solve it I've just changed the return value at "./lib/galaxy/web/controllers/dataset.py", at the "display" function (or method). In stead of returning the value returned by "open()" function, I do return the value returned by "read()" function. Originaly: ... return open(...) ... New: ... return open(...).read() ... Well, i don't know if its beacause of my system but i wish this can help Saludos Alfonso