PR#9848

The behaviour you quote is the documented behaviour in R 2.5.1.
Please do RTFM, especially ?install.packages:

      'install.packages' can be used to install new packages/bundles. It
      takes a vector of names and a destination library, downloads the
      packages from the repositories and installs them.  (If the library
      is omitted it defaults to the first directory in '.libPaths()',
      with a warning if there is more than one.)  If 'lib' is omitted or
      is of length one and is not a (group) writeable directory, the
      code offers to create a personal library tree (the first element
      of 'Sys.getenv("R_LIBS_USER")') and install there. Detection of a
      writeable directory is problematic on Windows: see the Warning
      section.

Now, it is entirely possible that Windows is mis-reporting on the 
permissions available, but that would not be a bug in R and one that is 
warned about (twice) on the help page.

That you can write a specific file there is not the issue, as the help 
page explains in detail.  You need to be able to write specfic types of 
files there, and a recent WinXP patch stops you being able to do that on 
networked drives.

Oops -- I meant R version 2.5.1, not 1.5.1.  My apologies.

So you did mean 1.4.1?  Two separate major version errors suggest that you 
really are insufficiently unaware of what you are using.

Brian D. Ripley,                  ripley at stats.ox.ac.uk
Professor of Applied Statistics,  http://www.stats.ox.ac.uk/~ripley/
University of Oxford,             Tel:  +44 1865 272861 (self)
1 South Parks Road,                     +44 1865 272866 (PA)
Oxford OX1 3TG, UK                Fax:  +44 1865 272595