[R-SIG-Mac] Greek font lost

[David Winsemius]

Dear MacRs;

I have been having this problem for a while, but thought that when I  
updated to 2.11.1 that it might get fixed, but just did that and it  
persists. When I use plotmath functions, I see little empty boxes  
where I should be seeing theta's and phi's:

require(graphics)  # the first plotmath example
x <- seq(-4, 4, len = 101)
y <- cbind(sin(x), cos(x))
matplot(x, y, type = "l", xaxt = "n",
         main = expression(paste(plain(sin) * phi, "  and  ",
                                 plain(cos) * phi)),
         ylab = expression("sin" * phi, "cos" * phi), # only 1st is  
taken
         xlab = expression(paste("Phase Angle ", phi)),
         col.main = "blue")
axis(1, at = c(-pi, -pi/2, 0, pi/2, pi),
      labels = expression(-pi, -pi/2, 0, pi/2, pi))
# -- no phi's or pi's or warnings ---

How do I identify which library should be replaced or repaired or  
added to my PATH or which option set?

Have searched archives and FAQs, but maybe I'm not using same terms or  
understanding what I am being told.

-- 

David Winsemius, MD
West Hartford, CT

sessionInfo()
R version 2.11.1 Patched (2010-06-14 r52281)
x86_64-apple-darwin9.8.0

locale:
[1] en_US.UTF-8/en_US.UTF-8/C/C/en_US.UTF-8/en_US.UTF-8

attached base packages:
[1] stats     graphics  grDevices utils     datasets  methods   base

other attached packages:
[1] lattice_0.18-8

loaded via a namespace (and not attached):
[1] grid_2.11.1  tools_2.11.1