R 2.11 on Mac OS X

Hello,

I've recently upgraded to R 2.11.1 on Mac OS X 10.8.4.   Now when I 
start R up I get the following message:

Error in identical(call[[1L]], quote(doTryCatch)) :
   7 arguments passed to .Internal(identical) which requires 5
Error in normalizePath(dirname(pkgpath), "/", TRUE) :
   3 arguments passed to .Internal(normalizePath) which requires 1
cannot find system Renviron

I get a similar message with user-defined functions ( i.e "X arguments 
passed when Y defined" ) though the functions appear to work.  This 
problem is also encountered when Rstudio fires up and so it cannot run now.

I did find a post that suggested it may be due to R accessing an old, 
possibly 32 bit library (I used to have 32 and 64 bit R installed and 
they both ran without trouble).  Possibly I need to completely clean out 
the installation and start again?  but I'm not sure precisely where the 
R support files are stored on Macs.  Can anyone give me a pointer and/or 
suggest an alternative fix?

Thank you

Norman Jessup