R running on my MacPro under OS X 10.6.8 no longer installs packages.  I
would greatly appreciate help in sorting this out.

Typically I get the messages like:
> install.packages("party")
Warning: unable to access index for repository
http://software.rc.fas.harvard.edu/mirrors/R/bin/macosx/leopard/contrib/2.13
Warning message:
In getDependencies(pkgs, dependencies, available, lib) :
  package ‘party’ is not available (for R version 2.13.1)

The repository URL mentioned in the first warning indicates leopard, not
snow leopard, the name for OS X 10.6.8.  Is this an issue?  If so, what to
do?

The second message seems to indicate that I might need a different version
of R.  If so, which?  How to preserve the existing version while checking
out the new version?

And version seems to indicate darwin9.8.0.  Any idea why?
> version
               _
platform       x86_64-apple-darwin9.8.0
arch           x86_64
os             darwin9.8.0
system         x86_64, darwin9.8.0
status
major          2
minor          13.1
year           2011
month          07
day            08
svn rev        56322
language       R
version.string R version 2.13.1 (2011-07-08)

Otherwise R is currently functioning fine.  I really don't want to screw
that up.  If there is a fix without installing a new version, I would like
to try that first.

I've never updated to a newer version, and it's been a while since I
installed on a mac, so step-by-step instructions are needed.

Thanks,

Carlisle

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