[R] Error on X11 or on R?

[Elio Mineo]

Dear list,
I am using R version 2.0.0 under Linux Mandrake 10.0. I have installed R 
by using the rpm file on CRAN.
By executing the following code, I have this output (the text file 
formaggio.txt is attached):

 > dati <- read.table("formaggio.txt", header=TRUE)
 > plot(dati)
Error in text.default(x, y, txt, cex = cex, font = font) :
        X11 font at size 16 could not be loaded

Is it a X11 problem or a R problem? What can I do to solve this problem?
Thanks in advance,
Elio
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