Problem with X11 fonts under Fedora 17.

I previously posted about this problem on the r-help list, but was told that I
should switch over to the r-sig-fedora list.  So here goes:

When trying to do a plot in a certain context I got an error:

Error in text.default(2, 6, main, cex = cex) :
 X11 font -adobe-helvetica-%s-%s-*-*-%d-*-*-*-*-*-*-*, face 1 at size 16 could not be loaded

This is reproducible (in my current environment) via:

par(mfrow=c(2,2))
plot(1:10)
text(2,6,"Oh, hell!",cex=2)

Can anyone tell me (in simple comprehensible terms, please) how I might
make the required font available so that it can be loaded?  I reiterate,
please keep it simple.  I find fonts toadally incomprehensible!

For what it's worth, here is my session info:

sessionInfo()
R version 2.15.2 Patched (2012-11-15 r61122)
Platform: x86_64-unknown-linux-gnu (64-bit)

locale:
 [1] LC_CTYPE=en_US.UTF-8       LC_NUMERIC=C
 [3] LC_TIME=en_US.UTF-8        LC_COLLATE=en_US.UTF-8
 [5] LC_MONETARY=en_US.UTF-8    LC_MESSAGES=en_US.UTF-8
 [7] LC_PAPER=C                 LC_NAME=C
 [9] LC_ADDRESS=C               LC_TELEPHONE=C
[11] LC_MEASUREMENT=en_US.UTF-8 LC_IDENTIFICATION=C

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

other attached packages:
[1] spatstat_1.30-0 deldir_0.0-21   mgcv_1.7-22     misc_0.0-15

loaded via a namespace (and not attached):
[1] grid_2.15.2     lattice_0.20-10 Matrix_1.0-10 nlme_3.1-105
[5] tools_2.15.2

NOTE:  In response to this query on r-help I received the suggestion that
I might need to install:

   xorg-x11-font-utils
   xorg-x11-fonts-75dpi
   xorg-x11-fonts-100dpi

I had xorg-x11-fonts-utils installed already, as it turned out, but managed to
install the other two packages via

   sudo yum install xorg-x11-fonts-75dpi.noarch
   sudo yum install xorg-x11-fonts-100dpi.noarch

After doing that things changed a *little* bit.  Instead of an error I got a warning:

In text.default(2, 6, "Oh, hell!", cex = 2) :
 X11 used font size 25 when 28 was requested 

and no actual characters appeared in the plot but rather 4 (???)
little rectangles outlined in dotted line type.

Any ideas as to how to alleviate *this* problem?

BTW my X11.options()$type is "Xlib".  I tried setting it equal to "cairo" but that
just made matters worse.  Doing plot(1:10) in a fresh X11() device gave the plot,
but with the axis labelling replaced by a few of those little dotted-line rectangles.

Thanks for any insight and advice.

   cheers,

       Rolf Turner